Triple flip, clinical magnet multiple polarity and placement timed sensing to prevent inadvertent actuation of magnet-mode in an active implantable medical device

ABSTRACT

The present invention changes the magnet-mode of an active implantable medical device (AIMD) such that repeated application of a clinical magnet in a predetermined and deliberate time sequence will induce the AIMD to enter into its designed magnet-mode. In one embodiment, a clinical magnet is applied close to and over the AIMD and removed a specified number of times within a specified timing sequence. In another embodiment, the clinical magnet is applied close to and over the AIMD and flipped a specified number of times within a specified timing sequence. This makes it highly unlikely that the magnet in a portable electronic device, children&#39;s toy, and the like can inadvertently and dangerously induce AIMD magnet-mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional application Ser.No. 63/174,498, filed on Apr. 13, 2021 and 63/215,429, filed on Jun. 26,2021.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention generally relates to active implantable medicaldevices (AIMDs), including cardiac pacemakers, implantable cardioverterdefibrillators (ICD), deep brain stimulators, spinal cord stimulators,and the like. The present invention is particularly important forpatients who have an AIMD with a magnet-mode. Placement of a permanent(i.e., time-constant) magnet over an AIMD has been used for many decadesas a simple way to place the device into magnet-mode to either suspendtherapy or enter a preset therapy mode. In fact, even before theintroduction of telemetric communication with pacemakers in the 1970s,magnets were used to alter pacing behavior in order to demonstratefunctionality such as remaining battery life or to achieve asynchronouspacing when electromagnetic interference (EMI) was suspected.

2. Prior Art

U.S. patent application Ser. No. 05/216,667 was filed on Jan. 10, 1972and is one of the earliest disclosures related to magnet-mode as a testfor assessing battery life or a patient's heart rate. The '667application subsequently issued as U.S. Pat. No. 3,774,619. The filingof the '667 application was just four years after the first implantablepacemaker patent (U.S. Pat. No. 3,391,697) issued on Jul. 9, 1968 toWilson Greatbatch. Currently, most cardiac pacemakers and implantabledefibrillators have a magnet-mode where a static magnet of a sufficientstrength (the clinical magnet) is placed over the AIMD implant. The AIMDsenses the static magnetic field and then switches into itspredetermined “magnet mode.” In general, a clinical magnet used for thispurpose is on the order of 70 to 120 Gauss.

Many deep brain stimulators and spinal cord stimulators also have amagnet-mode. Consequently, implantable medical devices, particularlycardiac implantable medical devices (CIED), are by design susceptible toexternal magnetic fields. Particular to this invention, externalmagnetic fields are called static magnetic fields because they provide aconstant magnetic field over time.

There has been a proliferation of relatively strong magnets being placedin portable electronic devices, toys, and the like. As will beexplained, there have been recent case reports of magnets built into acell phone causing implantable cardioverter defibrillators (ICD) andpacemakers to enter magnet-mode. In the case of an ICD, this is alarmingbecause magnet-mode suspends tachyarrhythmia detection and, therefore,suspends high-voltage therapy. Bearing in mind the gravity of suspendedtachyarrhythmia detection, that being suspension of life-saving therapydelivery, placing a magnet into a portable device, instrument, toy, andthe like, becomes a considerable concern as when a human impulsivelyplaces a strong magnet, such as contained in an iPhone 12, in a shirt,jacket or vest pocket, a bra, a fanny pack, a drug pump, or othersimilarly worn accessories or clothing. Many toddlers and even infantsreceive AIMD implants so the cohort of patients that play with toys issignificant. IPHONE® is a registered trademark of Apple Inc., Cupertino,Calif.

Such an impulsive action can inadvertently position the strong magnethoused inside the device unfavorably over an AIMD implant. Cardiacimplants including pacemakers and ICDs are typically implanted in apectoral pocket. Spinal cord stimulators are often implanted in thegroin or buttocks. Deep brain stimulators may also be pectorallyimplanted or they may be cranial implants or even both. The presence ofa strong magnet in close proximity to these types of implanted medicaldevices can cause dangerous and inadvertent activation of the device'smagnet-mode.

In that respect, inappropriate (even improper) interaction of the iPhone12 with an ICD has been the subject of recent worldwide news.Correspondingly, patient anxiety issues regarding cell phone safety havealso emerged. Medical doctors and pacemaker committee members, includingco-inventor Robert Stevenson, have received numerous calls from anxiouspatients. For example, a call recently received by Robert Stevensonconcerned a grandfather worried about his grandchild's iPhone 12Sentering his house. In the first place, a patient with tachyarrhythmiasgenerally experiences anxiety just knowing that they need to have anAIMD implant that shocks their heart when it chaotically beats. Worryingabout the safety of the implant can cause increased stress for a patientthat could possibly lead to other stress-induced health issues. Animportant effect of the present invention on a patient's mentalwell-being is that the present invention ensures the patient thatinadvertent magnet-mode entry of their implanted AIMD is mitigated(rendered highly unlikely) and even prevented by applying the deliberateand unique (novel) actions taught herein.

Even though both ICDs and pacemakers, by design, have a magnet-moderesponse, not all manufacturers' magnet-mode responses are identical. Ingeneral, however, for all ICDs, high-voltage therapy is suspended duringplacement of a magnet over the device, and for a cardiac pacemaker, theIPG is put into what's commonly known as a fixed rate or asynchronouspacing mode. During asynchronous pacing mode, if a bradycardia patientis not in bradycardia (in other words, has a normal heartbeat), a ratecompetition can occur. This means that the patient's underlying sinusrhythm is not in synchrony with the magnet-mode asynchronous beats ofthe cardiac pacemaker. Prolonged asynchronous pacing (for example, if apatient were to fall asleep with the magnet of their cell phonepositioned over their pocket all night) is not desirable. For somepatients, rate competition can result in reduced cardiac output alsoknown as reduced hemodynamic output, which can make the patient feel illincluding loss of energy. Also, prolonged asynchronous pacing isundesirable because it can lead to heart tissue remodeling.Additionally, a rare “pace on T” event (also known as a “r on T” event)can occur if the asynchronous pacemaker pulse repeatedly lands on thepart of the cardiac rhythm cycle known as the T wave. In this case,ventricular fibrillation (VF) can be induced, which is immediatelylife-threatening. Again, this is a very rare event.

There are also magnet-mode responses designed into other types ofimplantable medical devices, for example, deep brain and spinal cordstimulators. Testing the immunity of a cardiac implantable medicaldevice (CIED) to an electromagnetic field or electromagneticinterference (EMI) is defined by international ISO standard 14117. TheISO standard was originally known as AAMI PC69, of which coinventorRobert A. Stevenson was one of the original committee members (PC69became worldwide ISO Standard 14117 titled “Active implantable medicaldevices—Electromagnetic compatibility—EMC test protocols for implantablecardiac pacemakers, implantable cardioverter defibrillators and cardiacresynchronization devices”).

Robert A. Stevenson is also a United States Technical Representative toISO and part of the ISO 14117 Committee. For many years, Robert A.Stevenson has been the co-chairman of the United States PacemakerCommittee (Association for the Advancement of MedicalInstrumentation—Cardiac Rhythm Management Device Committee (AAMI-CRMD),additionally referred to as CRMD.

Since January 2021 after the first Heart Rhythm Society case reportemerged about an iPhone 12 causing an ICD to inadvertently entermagnet-mode, there has been a series of Pacemaker Committeeteleconferences. These meetings have been in conjunction with manydoctors, implantable device manufacturers and the FDA Office of Scienceand Engineering Labs. Testing by the FDA has confirmed that the staticmagnetic fields emanating from an iPhone® 12 greatly exceed the 10 Gauss(1 mT) limit required for an implantable device to enter magnet-mode atthe approximate depth which an ICD or an IPG is typically implanted in apatient, as specified in ISO 14117. The FDA has confirmed that thestatic magnetic fields emanating from the top of an iPhone 12 aregreater than 300 Gauss (30 mT), which far exceeds the ISO 14117 10 Gausslimit. The FDA has also confirmed that strong magnetic fields in excessof 700 Gauss (70 mT) are produced by the Apple watch.

Table 1 below summarizes the static magnetic field mapping datapresented by the FDA to the Pacemaker Committee on Mar. 3, 2021 (alldata in Gauss).

TABLE 1 EUT model iPhone 12 iPhone 12 iPhone 12 Apple Distance Pro MaxPro iPhone 12 Mini Watch  1 mm** 363 — — — —  1 mm* 114 84 90.7 59.9 77811 mm* 15.2 16.7 16 13.1 34.5 21 mm* 7.9 8.5 8.1 6.5 6.7 31 mm* 3.6 3.73.7 3.1 1.8 *Measured from the top of camera or from the top of thewatch **Measured from the top of phone main body

It was in this context that co-inventors Michael Steckner and RobertStevenson collaborated on how to prevent inadvertent entry of an AIMDinto magnet-mode.

At the outset, it should be mentioned that there are other approachesfor a safer alternative to magnet-mode that the inventors studied anddiscarded. The first approach was to simply eliminate AIMD magnet-mode.However, many of the physicians who participated in theseteleconferences have pointed out that a simple way to enter magnet-modewas essential. Some of the reasons why an emergency responder, doctor,surgeon or even the patient may place a magnet over an AIMD include:

1) Sometimes an ICD has a lead failure or other issue, which can causethe device to repeatedly deliver painful and inappropriate high-voltageshocks. In this situation, a magnet is quickly placed over the ICD tosuspend such painful shocks while the patient is transported to anappropriate hospital, and the like.

2) In a pacemaker patient, and this depends on individual programming,positioning a magnet over the medical device places the pacemaker in anasynchronous pacing mode that could be at a higher pacing capturethreshold than the patient needs. In other words, for a patient incardiac distress, placing a magnet over the medical device canimmediately cause the pacemaker to pace at a higher level than what theyneed, again, during the time that the patient is being transported orevaluated.

3) During surgery it is common practice to place a magnet over thepatient's implanted device, for example, to suspend deep brainstimulation, suspend spinal cord stimulation or for an ICD to suspendhigh-voltage shock therapy. ICD therapy is frequently suspended, forexample, during a delicate surgery like a robotic-assisted pancreasresection. The reason is that should an automatic high voltage shockfrom an AIMD occur, the shock could cause the sedated patient's body tosuddenly and violently jump (surgeons call this “jumping off thetable”). For example, one thing that could cause an ICD to deliver anautomated high voltage shock during surgery is electromagneticinterference noise produced by electrocautery. However, temporarilyplacing an AIMD in magnet-mode during surgery is not a concern becausethe patient's EKG waveforms are being continuously monitored by theanesthesiologist during surgery. Should the patient need to bedefibrillated during surgery, therapy can be performed by an externalcardiac defibrillator.

Several Pacemaker Committee doctors have also pointed out that theclinical donut-shaped magnets that are used to deliberately place anAIMD into magnet-mode are present world-world from little clinics toemergency rooms to hospitals to ambulances, and the like. Consequently,magnet-mode represents a universal long-standing and highly regardedprotocol for rapid intervention. The present inventors also studiedexisting BLUETOOTH-enabled devices that can communicate with an AIMD.(BLUETOOTH is a registered trademark of Bluetooth Sig, Inc., Kirkland,Wash.)

Cell phone apps were also examined. The problem with a cell phone app ishow rapidly a secure connection can be established with an ICD and theability of an ICD-dependent patient to self-administer when painful highvoltage shocks are being discharged into their body. Moreover, there isan inherent cyber security benefit in having to place a clinicaldonut-shaped magnet directly over the patient's implant. The staticclinical magnets that are used to induce magnet-mode are about 70 to 120Gauss and only work in close proximity to the implanted AIMD (closerthan about 15 cm or six inches). The longstanding practice of placing astatic magnet over the patient's AIMD is inherently cyber securitysecure because the magnet must be in very close proximity to thepatient's skin or clothing, which is an invasion of the patient's spacethat the patient would generally be aware of. In addition, many remoteareas and clinics around the world do not have cellular phone coverageand some clinicians do not even own a cell phone.

One of the concerns with any wireless or BLUETOOTH® attempt atcommunication with an AIMD is that such communication could inducemagnet-mode over a greater distance which could open up the threat forhackers, and the like. ISO 14117 has a clause that specifies that noCIED (pacemaker or ICD) can enter magnet-mode at a static magnetic fieldstrength below 1 millitesla (10 Gauss). However, this is as much a humanfactor situation as it is one of technical specifications. InternationalStandards and National Standards that limit the fields from an emitterare not always in harmony with ISO 14117.

Human factors are a great concern when analyzing any AIMD/CIED potentialstatic magnetic field interaction. For example, stereo speakers, such astower speakers used in a home theater system, have very powerfulmagnets. If an AIMD-dependent patient removed one of these speakers fromits cabinet and then flipped the speaker over so that the strong magnetis placed directly over their implant, this could cause their implanteddevice to enter magnet-mode. While such a scenario is highly unlikely,one could even argue that instead of inadvertent entry into magnet-mode,it was deliberate.

A recent case reported in a Heart Rhythm Society (HRS) prepublicationtitled: Life Saving Therapy Inhibition by iPhones Containing Magnets,Greenberg, M. D. et al., describes that when an iPhone 12 was placedover a patient's pectoral area, the phone's magnet undesirably inducedan ICD magnet-mode. This was validated and verified by the FDA Office ofScience and Engineering Laboratories (FDA-OSEL). In comparison toprevious iPhone® models, the iPhone 12 and the newer iPhone 13 have asystem called MAGSAFE®, which means that a powerful permanent ringmagnet that produces a static magnetic field resides inside the phone toassist in alignment of the phone with an external wireless chargingdocking pad, wireless charging wand, and the like. MAGSAFE is primarilydesigned to work with a coiled wire in the external charging device thattransmits a time varying magnetic field intended to couple its energy ina transformer-like action to a charging coil embedded in the iPhone 12.An Apple watch can be charged in a similar manner.

The CRMD has a formal relationship with the FDA, the Heart RhythmSociety and its doctors and clinicians. In particular, members of theHRS Health Policy Committee and Interoperability Workgroup are membersof the Cardiac Rhythm Management Device (CRMD) Committee and vice versa.The CRMD has been made aware that Samsung and other Android cell phonemanufacturers may also be incorporating permanent magnets into theirdevice. This has not yet been validated. However, Greatbatch Ltd.,Clarence, N.Y., has obtained high-resolution CT images of an iPhone 12,an iPhone 13 and an Apple watch. These images, which were provided tothe CRMD Committee and are included herein (see FIGS. 8A, 8B and 8C),show a large permanent charging alignment ring magnet 232 housed insidethe device. It should be pointed out that neither Apple nor any othermanufacturer of portable electronic devices containing a magnet hasviolated any standard or any regulation. This is simply an unregulatedspace. Again, inadvertently placing a cardiac implantable medical device(CIED) or AIMD in magnet-mode is as much a human-factor concern asanything.

A first step in working with the FDA Office of Science and EngineeringLabs (OSEL) was to precisely map the static magnetic fields of aniPhone® 12 and Apple watch at various distances and spatial orientations(Reference: Table 1 above). CRMD and the present inventors then comparedthe static magnetic fields produced by the iPhone® to ISO 14117 toassess the potential for interference with an ICD or pacemaker or othertype of AIMD. The static magnetic field maps of the iPhone 12 were foundto greatly exceed the ISO 14117 magnet-mode threshold.

There have also been a number of reports of the relatively weakermagnets in earbuds or the relatively small and weaker magnet in an iPador a Kindle cover inducing a magnet-mode response in an AIMD. The CRMDhas been watching these papers for years and has conducted numerousinterviews with the authors to assess the human factors. In each case,the author reported it was difficult to find the “sweet spot” thatinduced magnet-mode and it was particularly difficult to hold ontomagnet-mode, particularly with any movement of the patient. The CRMDCommittee has looked at these situations and concluded that it would behighly unlikely for an iPad or a Kindle cover type of device containinga magnet to induce a prolonged (not transient) and, therefore, dangerousmagnet-mode response.

However, a recent case report involving an iPhone 12 is of concern froma human-factor point of view. It is common surgical practice to positiona cardiac implantable medical device (CIED) or AIMD in a pectoralpocket. The CIED is then connected to one or more leads that are routedtransvenously to distal electrodes in contact with cardiac tissue. Aspreviously described, when a relatively strong magnet (clinical magnet)is placed directly over the CIED, the device's magnet sensors aredesigned to put the device into magnet-mode. Older style (legacy) CIEDshave reed switch sensors that switch in the presence of a strongmagnetic field (a reed switch is unable to detect north-south polaritybut can detect the minimum amplitude of the static magnetic field). Mostpresent-day implantable devices use a Hall-effect sensor which isdesigned to detect a static magnetic field of specified amplitude(Hall-effect sensors can be programmed to detect north-south orsouth-north magnetic field polarity, however, no AIMD is presentlydesigned or programmed to do so). A giant magnetorestive (GMR) sensor,which is rarely used in current AIMD designs, cannot be programmed todetect north—south clinical magnet reversals. This is yet another reasonfor the alternative to count multiple placements within specifiedconstraints (ref. FIG. 9 ). This enables AIMDs with Hall-effect and GMRbased sensors, and the like, to be more resistant to inadvertent entryinto magnet-mode.

As used herein, “n” comes from mathematics, meaning “n” can be anynumber. The letter “n” can be the number of placements, “n” can be thenumber of flips, or “n” can denote an application time in seconds orremoval time in seconds. The letter “n” with subscripts, for example,can be used to specify a minimum and a maximum placement or clinicalmagnet removal time. In summary, and as defined herein, the use of theletter “n” has to be taken in context as it can have multiple meanings.

Thus, a feature of the present invention is to: 1) detect and countmultiple placements of the magnet over the AIMD or, 2) sense thepolarity (north-south) flips of the static magnetic field emanating froma clinical magnet (the N-S flip counting is a preferred embodiment asthis is the most resistant to inadvertent magnet-mode entry). Ideally,these two approaches are integrated into one methodology. This wouldrequire reprogramming the AIMD to either sense the number of placementswithin a specific time period (“n”-placements) or, to detect the numberof polarity flips within a specific time frame. Older legacy style AIMDsor even newer AIMDs with reed switches cannot be programmed to detectnorth or south polarity from a clinical magnet. However, in contrastwith a mechanical reed switch and in accordance with the presentinvention, most AIMDs now have an electronic Hall-effect sensor that canbe programmed or even re-designed to detect north-south polarityreversals (or flips) from a clinical magnet. That is even though no AIMDin use today is programmed to do so.

In a preferred embodiment of the present invention, a new clinicalmethod is described wherein: a clinical magnet (without the clinician orpatient placing the magnet needing to know which side is north or south)is simply placed over the AIMD for a time (for example, count to threein one's head), then the magnet is removed again (count again), flippedover (count again), and then the magnet is repositioned over the AIMD.This sequence can be repeated for any number of times “n”. In this case,when “n” is defined as the total number of flips, and when n=3, theprocedure is referred to as the “Triple Flip”, (international cardiacsocieties are contemplating the number of flips and placements of theclinical magnet over the AIMD implant). In this way, all clinicalmagnets would be repetitively placed, timed and flipped. It is notimportant that the clinician understand whether the AIMD is sensing thenumber of placements and time periods or that the AIMD is also sensingthe placements and the number of north-south polarity reversals (flips)as the clinical methodology is the same for both situations. Note that“n” flips require n+1 placements.

It would be highly unlikely to remove an iPhone 12 or an iPhone 13 froma shirt pocket for a few seconds and then place it back in the pocket,then remove it from the pocket for a similar number of seconds and thenplace it back in the pocket (“n”-number of times). It is even moreunlikely that the cell phone would be flipped each time, which wouldrequire n+1 placements, each time doing a north-south polarity reversal.Further, the measured static magnetic fields emanating from the back ofan iPhone are much higher than at the front face of the phone, so it isfurther unlikely that an iPhone could inadvertently induce north-southor south-north flips (this depends upon implant depth below the skin,patient body-mass-index (BMI) and other factors).

In that respect, it is a goal of the present invention that the multipleplacements or polarity flips of a clinical magnet over an AIMD becompatible with almost all AIMD design platforms in the world. Again, asstated, this is going to require AIMD reprogramming (or is some casesre-design) in order to detect the number of magnet placements and theirtiming or the number of magnet flips, or both, before the device entersinto magnet-mode. It is contemplated that the clinician would use asurgical skin marker, a piece of tape (a tape dot) or equivalent toplace a dot on the patient's skin or clothing over the implant so thatthe clinical magnet is repositioned over the AIMD in the same mannerafter each placement or flip.

ISO 14117 does not specify the static magnetic field strength at whichan implantable device must enter magnet-mode. Instead, ISO 14117specifies the magnetic field floor below which the device must not entermagnet-mode. The ISO 14117 magnetic field floor is specified as 1millitesla (i.e., a 10 Gauss limit). As will be described hereinafter inthe detailed description of the invention, the present inventors believethat, from a human-factors point of view, building any portableelectronic device that can be placed in a shirt pocket or over animplant for an extended period of time, is potentially dangerous in thatthe AIMD may inadvertently (inappropriately) enter into magnet-mode.NOTE: this ISO 14117 10 Gauss level has a +/−1 Gauss tolerance, whichmeans that an AIMD can enter magnet-mode at 9 Gauss (0.9 mT). Hence, asthe growing popularity of consumer products with powerful magnets islikely to become even more common in the future, it is incumbent thatthe magnet-mode response of an AIMD be changed in order to avoid agrowing and potentially life-threatening patient safety concern.

Reference is now made to a paper presented at the Heart Rhythm SocietyAnnual Scientific Sessions on Jul. 29, 2021 by Dr. Charles Swerdlow, MD,Fellow of HRS and a member of the faculty at Cedars Sinai MedicalCenter. The title of the paper is “CIEDs and Static Magnetic Fields2021.” During preparation of the paper (assisted by Robert Stevenson),several interesting new static field emitters were documented. They aresummarized as follows: 1) wristbands for watches that have a magneticclasp significantly exceed 10 Gauss, 2) a wrist worn magnetic tool beltthat holds devices like an Allen wrench, and the like, has a verypowerful magnet, 3) magnetic implants to hold jewelry in place, 4)magnetic badge buttons, and 5) a Nikken 1 Power chip Medallion Charmmanufactured by Kenco, which is attached to a lanyard worn around theneck or placed over any body area. The Nikken 1 advertises a magneticfield strength of 900-1000 Gauss. This is very worrisome as 10-Gauss isthe ISO 14117 limit for CIED magnet mode. One of the CRMD members haspointed out that children's toys are also starting to show up withstrong magnets, such as a large teddy bear that has a magnet that allowsit to be stuck on the refrigerator. It seems that with the reduced costand availability of neodymium there is a proliferation of devices withstrong magnets.

There are also two other case reports of interest. The first is titled,Smart Wearable Device Accessories May Interfere with Implantable CardiacDevices. The citation for this article is: Asher Eb, Panda N, Trend Ct,Wu M, Smart Wearable Device Accessories May Interfere with ImplantableCardiac Devices, Heart Rhythm Case Reports (2021). The key takeaway fromthis article is that magnets used in the wristbands of fitness trackersand Smart watches, and the like, can interfere with implanted cardiacdevices through inducing an inappropriate magnet-mode response.

Another Heart Rhythm Society case report which comes from theCardiovascular Arrhythmia Service, Brigham and Women's Hospital andHarvard Medical School is titled, Unintentional Magnet Reversion of AnImplanted Cardiac Defibrillator by An Electronic Cigarette, authored byTedrow, M. D. et al.

The present inventors are also aware of a recent case report out ofCalgary, Canada involving a patient with a spinal cord stimulator (SCS).The SCS was designed with a magnet-mode, which means that when aclinical magnet is applied to the device, therapy is suspended so thatthe patient can control the device using an external handheldprogrammer. The handheld programmer can turn the SCS on and off, selectwhat electrodes the patient wants to use to deliver pain relief therapy,adjust the amplitude of the waveforms, all while therapeutic electricalpulses are being sent to the spine. In this patient, the SCS wasimplanted low in the patient's groin on the right side. Consequently,when the patient placed an iPhone 12 in the front pocket of his pants,the first indication that something was wrong was when the patientsuddenly experienced severe lumbar spinal cord pain. The patient did notunderstand what was happening and in pain, started to twist and contortin an attempt to get himself into a more comfortable position. It isknown that twisting and contorting can cause the electrode bundle thatis in the spinal cord canal to shift, which can change the efficacy ofthe therapy being delivered. Spinal cord stimulator patients aregenerally provided with an external control device (a patient handheldprogrammer) so that they can regulate the active electrode pairs,stimulation therapy and even the waveforms that mitigate pain. Painmitigation is known as maximum paresthesia (paresthesia that overridesthe pain sensations and stops them from transiting to the spinal cordnerve).

By shifting and contorting in an attempt to relieve pain, the Calgarypatient's iPhone 12 was inadvertently being intermittently positionedover the SCS implant. By design, re-application of a magnet turns theSCS back on so that therapy is once again delivered. It is likely thatthe electrode bundles in the patient's spinal column had shiftedsufficiently such that, when the SCS was turned back on, the deliveredtherapy caused the patient to experience a jolting, stabbing pain thatsent the patient to the floor. The patient described the experience assimilar to being tasered or receiving a powerful electrical shock.Amazingly, the patent at a later time, laid on his back without moving(in other words, so the electrode bundles didn't shift) and discoveredthat he could repeatedly turn on and off his SCS therapy with the iPhone12. The Calgary patient further reported that his situation could havebeen markedly worse had he been driving when the initial jolting shockoccurred.

It is also noted that a deep brain stimulator (DBS) has a similarmagnet-mode where proper placement of a clinical magnet is designed tosuspend therapy. Suspension of therapy in a patient with severeParkinson's or Tourette's Syndrome, for example, can lead touncontrolled and sometimes violent patient motions, which cannot becontrolled without a DBS. A human-factor concern regarding DBS devicesis that if therapy is inadvertently suspended, for example, while thepatient is operating a motor vehicle, uncontrolled tremors could resultin an automobile accident.

It is also noted that a deep brain stimulator senses electrical brainwave activity to provide therapy to prevent an epileptic seizure fromoccurring. Candidates for a deep brain stimulator implant typicallyexperience fairly frequent epileptic seizure episodes. It is the generalpractice that such patients are not able to have a driver's license.However, after implantation of a DBS device to prevent epilepticseizures, these patients can return to normal daily life activities,including driving. This presents another potential human-factor issuewhere inadvertent placement of a magnet over the DBS could suspenddevice therapy. If suspension of device therapy were to happencoincident with the onset of a seizure, this could of course, be verydangerous, for example, when the patient is driving a motor vehicle.

Refer now to U.S. Pat. No. 8,600,505, which relates to anexternally-controlled Vagus nerve stimulator (VNS) for “treating chroniccardiac dysfunction”. Beginning on column 15, line 51, this patentdescribes that “[o]rdinarily, the surface 101 of the patient magnet mustbe applied to or swiped, that is, moved in a continuous motion, over theneurostimulator 12 for at least one second to protect against the reedswitch 30 being inadvertently triggered by other magnetic sources.”Then, beginning at column 16, line 17, the '505 patent states that,“[t]he instructions 104 can walk the patient 10 through the individualphysical steps necessary to properly use a magnet, including what swipepattern to use and providing a countdown of how long to hold the magnetover the neurostimulator 12.” At column 16, lines 28, the '505 patentstates that, “[t]ypically, a neurostimulator 12 will inhibit stimulationindefinitely for as long as a patient magnet 100 remains in place. If apatient 10 suffers a crisis, such as significant pain or discomfort, VNScan be stopped for an indefinite amount of time by fixing the patientmagnet 100 in place over the neurostimulator 12, such as by taping themagnet to the chest, until professional help can be sought.”

When one considers the large and powerful ring magnet in the back of aniPhone 12 and imagines, for example, placing the iPhone 12 in the upperpocket of a fly-fishing vest, one can see the potential for repeated andinadvertent swipe patterns. The cell phone pocket for a fly-fishing vestis placed high in the pectoral area directly over where an AIMD wouldtypically be implanted. A fly-fisherman is constantly contorting hischest and could be moving or swiping the iPhone 12 almost continuallyover the implant. It is hard to imagine how many inadvertentapplications of magnet-mode or different therapy levels might beinduced.

Referring back to the '505 patent, the disclosure beginning on column17, line 10 describes “through magnet-mode, such as one swipe signalinga one-hour suspension, two swipes signaling a four-hour suspension, andthree swipes signaling an eight-hour suspension for when the patientgoes to bed and wants to suspend stimulation while he is asleep.” The'505 patent goes on to state, “[o]ther manner of accommodating multiplestimulation modes are inefficient for the use of a patient magnet 100are possible.” Again, given the proliferation of powerful magnets, suchas in the iPhone 12, one can see that the '505 patent is another exampleof a very dangerous situation where inadvertent entry into magnet-modecould suspend important therapy for long periods of time.

SUMMARY OF THE INVENTION

The present invention resolves the concerns discussed above regardinginadvertent or inappropriate entry into magnet-mode for an AIMD whenexposed to an electronic device, such as an iPhone 12 or iPhone 13, achild's toy with a strong magnet, and the like. The invention disclosedherein applies to AIMDs with both older generation reed switches, GMRsensors and newer generation AIMDs that generally have an internalHall-effect sensor, also known as a magnetic field sensor. Moreparticularly, in one embodiment, the present invention teachesreprogramming an AIMD with a magnet-mode that can detect a number ofplacements of a clinical magnet over the implanted AIMD within aspecified time period and for a specified duration and only then doesthe AIMD enter into magnet-mode. In another embodiment, the presentinvention teaches deliberately flipping a clinical magnet (e.g., magnetpolarity inversion) over an AIMD multiple times in a particular timesequence, which significantly reduces the likelihood of inadvertentmagnet-mode and effectively mitigates and prevents an AIMD from beinginadvertently triggered (switched) into magnet-mode.

In one embodiment, flipping the magnet is known as “The Double-Flip”.The Double-Flip is attained when a clinician first places a magnet overthe AIMD, then flips the magnet over and places the opposite polarity ofthe magnet against the AIMD, followed by a second flip with placement ofthe magnet back to its original polarity over the AIMD. Polaritysensitivity is realized with Hall-effect or alternative similar sensorsinternal to the AIMD, where the novel circuitry described by the presentinvention is programmed to enter magnet-mode on detecting a defined flipand time sequence. Three clinical magnet flips relate to the title ofthe invention, which embodies the “The Triple Flip”, which requires fourplacements of the clinical magnet within a specified time sequence.

In summary, the present invention relates to reprogramming an AIMD witha magnet-mode so that either multiple placements of a clinical magnetover the device within a specified time period are sensed or multipleplacements of a clinical magnet over the device while each time flippingthe magnet are sensed by the device. From the clinician's point of viewwhen placing a clinical magnet over a device, the clinician does notneed to know how the AIMD is designed or re-programmed to sense thestatic field from the magnet or the magnet's polarity. All the clinicianhas to do, for example, for “The Triple Flip” technique, is to place theclinical magnet over the AIMD within a specified period of time (fourtimes), each time turning the magnet over so that there is a north-southreversal. The AIMD is programmed to count this as a specified number ofmagnet placements, or if the device has the capability of detectingnorth or south polarity, the AIMD will also record the number of flips.In either case, the result is that the AIMD will enter magnet-mode afterthe proper number of placements of the clinical magnet over the AIMD orthe proper number of placements of the clinical magnet over the AIMDalong with the proper number of flips.

The present invention also teaches another feature that often ariseswhen an AIMD patient, such as a CIED patient, is being transported in amedical emergency, for example, in an ambulance. While rare, fromtime-to-time an ICD patient can have a defective lead that becomes“noisy”, thereby causing the ICD to falsely detect and continuouslydeliver painful and inappropriate high-voltage shocks. In this case, theclinical magnet is first placed over the ICD to suspend high-voltagetherapy and then the magnet is taped in place until the patient reachesa hospital, a pacemaker center or a clinic where the device or leads canbe replaced (or at least re-set). The present invention includes afeature within the AIMD programming where once the proper number ofplacements or flips have been detected and the device entersmagnet-mode, the AIMD stays in magnet-mode for a programed period oftime or for as long as either the north or the south face of theclinical magnet is in place over the device (taped in place).

As such, the primary purpose of the present invention is to prevent anAIMD from inadvertently entering magnet-mode. A secondary purpose of thepresent invention is to preserve the usefulness of the millions ofclinical magnets that are in doctor's offices, hospitals, emergencyrooms, stuck on file cabinets, in ambulances, and even in remote areasof the world without electricity. Preventing an AIMD from beinginadvertently triggered into magnet-mode is crucial to patient safety,particularly in light of the proliferation of permanent magnets, notonly in the iPhone 12 and the iPhone 13 and their ring magnet designs,but also in smart watches including the APPLE® watch, magnet wristbands, KINDLE® covers (KINDLE is a registered trademark of AmazonTechnologies, Inc., Seattle Wash.), iPAD® covers (iPAD is a registeredtrademark of Apple Inc., Cupertino, Calif.), FITBITS®, (FITBIT is aregistered trademark of Fitbit, Inc., San Francisco, Calif.) certainelectronic cigarettes and even magnetic earbuds, and the like.

Further regarding the iPhone 12, when a cell phone is naturally andnaively placed in a person's shirt pocket, coat pocket, vest pocket(e.g., a fly-fishing vest pocket), bra, under garment pocket, fanny packor other similarly worn accessories or clothing, the magnet of theiPhone 12 can inappropriately suspend ICD high-voltage therapy (theseare typically implanted in a pectoral pocket which could align with ashirt pocket, etc.). This could endanger the life of a patient should adangerous tachyarrhythmia arise. Suspending life-saving high-voltageshock therapy for an extended period of time is potentially harmful andeven life-threatening to the patient because, if the patient enters intoa dangerous arrhythmia, such as ventricular fibrillation (VF), the ICDwould be disabled and unable to provide high-voltage, life-saving shocktherapy to the patient's heart. With a powerful magnet inappropriatelyheld over the ICD, the ability to deliver a high-voltage shock to achaotically beating heart is prevented. In other words, as long as themagnet is sensed by the ICD, it is not possible for the ICD tocardiovert the patient's chaotic heart rhythm into a life-sustainingheart rhythm. However, the double or multiple magnet applications ormagnet flips of the present invention effectively prevents suchlife-threatening situations.

Additionally, a triple magnet application or triple magnet flip (ormore, including n-flips) according to the present invention provides aneven higher degree of patient safety. As disclosed herein, these magnetapplications or magnet flips must be performed within a specific timesequence so that inadvertent entry into AIMD magnet-mode becomes evenmore unlikely.

Further, a recent sequence of CT scans taken by Greatbatch Ltd.,Clarence, N.Y., of an iPhone 13 show that the phone has a similar oreven larger toroidal magnet as previously described for an iPhone 12. Inaddition, Apple's worldwide warnings include advising patients to keepan iPhone 12 or an iPhone 13 at least 15 cm (6 inches) from an implantedAIMD. In other words, the present concern is certainly not limited tojust the iPhone 12.

Thus, the present invention relates to an active implantable medicaldevice (AIMD), comprising a housing for the AIMD, the housing containinga magnet-detection sensor connected to electronic circuits, wherein theelectronic circuits have been programmed to register when themagnet-detection sensor detects that a magnet is in close proximity tothe AIMD as a first proximity occurrence, and wherein, within a definedfirst-time window upon commencement of the first proximity occurrence,the electronic circuits have been programmed to register when themagnet-detection sensor no longer detects that the magnet is in closeproximity to the AIMD as a first removal occurrence, and wherein, withina defined second-time window upon commencement of the first removaloccurrence, the electronic circuits have been programmed to registerwhen the magnet-detection sensor again detects that the magnet is inclose proximity to the AIMD as a second proximity occurrence to therebycause the electronic circuits of the AIMD to enter into magnet-mode.Further, upon commencement of the second proximity occurrence, theelectronic circuits have been programmed to remain in magnet-mode for aslong as the magnet-detection sensor detects that the magnet is in closeproximity to the AIMD, wherein the magnetic-detection sensor isconfigured to detect the close proximity of the magnet having a strengthof at least about 9 Gauss. The magnet-detection sensor is selected fromthe group of a reed switch, a Hall-effect sensor and a giantmagnetoresistive (GMR) sensor. Further, the first-time window has aduration of from n₁ seconds to n₂ seconds, and the second-time windowhas a duration of from n₃ to n₄ seconds, wherein n₁ and n₃ seconds arethe same or different and n₂ and n₄ seconds are the same or differentor, the first-time window has a duration of from 2 to 10 seconds, andwherein the second-time window has a duration of from 2 to 10 seconds.

The present invention further relates to an AIMD wherein, instead ofentering into magnet-mode upon commencement of the second proximityoccurrence, the electronic circuits have been programmed not to enterinto magnet-mode upon commencement of the second proximity occurrence,and wherein, within a defined third-time window upon commencement of thesecond proximity occurrence, the electronic circuits have beenprogrammed to register when the magnetic-detection sensor no longerdetects that the magnet is in close proximity to the AIMD as a secondremoval occurrence, and wherein, within a defined fourth-time windowupon commencement of the second removal occurrence, the electroniccircuits have been programmed to register when the magnetic-detectionsensor again detects that the magnet is in close proximity to the AIMDas a third proximity occurrence to thereby cause the electronic circuitsof the AIMD to enter into magnet-mode, and wherein, upon commencement ofthe third proximity occurrence, the electronic circuits have beenprogrammed to remain in magnet-mode for as long as themagnetic-detection sensor detects that the magnet is in close proximityto the AIMD.

The present invention further relates to an AIMD wherein, instead ofentering into magnet-mode upon commencement of the second proximityoccurrence, the electronic circuits have been programmed not to enterinto magnet-mode upon commencement of the second proximity occurrence,and wherein, within a defined second plus x-time window aftercommencement of the second proximity occurrence, the electronic circuitshave been programmed to register when the magnetic-detection sensordetects that the magnet is no longer in close proximity to the AIMD as afirst plus x additional removal occurrence, and wherein, within adefined second plus x+1-time window after commencement of the first plusx removal occurrence, the electronic circuits have been programmed toregister when the magnetic-detection sensor again detects that themagnet is in close proximity to the AIMD as an additional proximityoccurrence to thereby cause the electronic circuits of the AIMD to enterinto magnet-mode, wherein x in the second plus x-time window is the sameas in the first plus x additional removal occurrence and in the secondplus x+1-time window, and wherein x=1 to 100, and wherein, upon theadditional x+1 proximity occurrence, the electronic circuits have beenprogrammed to remain in magnet-mode for as long as themagnetic-detection sensor detects that the magnet is in close proximityto the AIMD.

The present invention further relates to an AIMD that comprises a leadwire connected to the AIMD, wherein the lead wire extends to a distalelectrode in contact with biological cells for providing electricaltherapy to the biological cells, and wherein, upon commencement of thesecond proximity occurrence, the electronic circuits have beenprogrammed to enter into magnet-mode so that either the AIMDdiscontinues providing electrical therapy to the biological cells or theAIMD enters into a preset therapy mode for providing electrical therapyto the biological cells, and wherein, upon commencement of the secondproximity occurrence, the electronic circuits have been programmed toremain in magnet-mode for as long as the magnetic-detection sensordetects that the magnet is in close proximity to the AIMD.

The present invention further relates to an AIMD having electroniccircuits that have been programmed to register when themagnetic-detection sensor detects that the magnet has either a north ora south polarity facing the AIMD as the first proximity occurrence, andwherein, within the defined first-time window upon commencement of thefirst proximity occurrence, the electronic circuits have been programmedto register when the magnetic-detection sensor no longer detects thatthe magnet is in close proximity to the AIMD as the first removaloccurrence, and wherein, within the defined second-time window, theelectronic circuits have been programmed to register when themagnetic-detection sensor detects that the magnet has been flipped sothat the other of the north or the south polarity is in close proximityto the AIMD as the second proximity occurrence to thereby cause theelectronic circuits of the AIMD to enter into magnet-mode.

The present invention also relates to an active implantable medicaldevice (AIMD) comprising a housing for the AIMD, the housing containinga magnet-detection sensor connected to electronic circuits, wherein theelectronic circuits have been programmed to register when themagnetic-detection sensor detects that a magnet is in close proximity tothe AIMD as a first proximity occurrence, and wherein, within a definedfirst-time window of at least n₁ seconds to a maximum of n₂ seconds uponcommencement of the first proximity occurrence, the electronic circuitshave been programmed to register when the magnet-detection sensor nolonger detects that the magnet is in close proximity to the AIMD as afirst removal occurrence, and wherein, within a defined second-timewindow of at least n₃ seconds to a maximum of n₄ seconds uponcommencement of the first removal occurrence, the electronic circuitshave been programmed to register when the magnetic-detection sensoragain detects that the magnet is in close proximity to the AIMD as asecond proximity occurrence to thereby cause the electronic circuits ofthe AIMD to enter into magnet-mode, and wherein n₁ and n₃ seconds arethe same or different and wherein n₂ and n₄ seconds are the same ordifferent, and wherein, upon commencement of the second proximityoccurrence, the electronic circuits have been programmed to remain inmagnet-mode for as long as the magnetic-detection sensor detects thatthe magnet is in close proximity to the AIMD or wherein, instead ofentering into magnet-mode upon commencement of the second proximityoccurrence, the electronic circuits have been programmed not to enterinto magnet-mode upon commencement of the second proximity occurrence,and wherein, within a third-time window of at least n₅ seconds to amaximum of n₆ seconds after commencement of the second proximityoccurrence, the electronic circuits have been programmed to registerwhen the magnetic-detection sensor no longer detects that the magnet isin close proximity to the AIMD as a second removal occurrence, andwherein, within a defined fourth-time window of at least n₇ seconds to amaximum of n₈ second after commencement of the second removaloccurrence, the electronic circuits have been programmed to registerwhen the magnetic-detection sensor again detects that the magnet is inclose proximity to the AIMD as a third proximity occurrence to therebycause the electronic circuits of the AIMD to enter into magnet-mode, andwherein, upon commencement of the third proximity occurrence, theelectronic circuits have been programmed to remain in magnet-mode for aslong as the magnetic-detection sensor detects that the magnet is inclose proximity to the AIMD.

The present invention also relates to a method for having an activeimplantable medical device (AIMD) enter into magnet-mode, the methodcomprising the steps of: providing an AIMD housing a magnet-detectionsensor connected to electronic circuits, wherein the electronic circuitshave been programmed to register when the magnetic-detection sensordetects a defined sequence when a magnet is moved in and out of closeproximity to the AIMD to thereby cause the electronic circuits to enterinto magnet-mode; providing a magnet of a defined Gauss; moving themagnet into close proximity to the AIMD so that the electronic circuitsregister when the magnet-detection sensor detects the magnet as a firstproximity occurrence; then, within a defined first-time window aftercommencement of the first proximity occurrence, moving the magnet awayfrom the AIMD so that the electronic circuits register when themagnet-detection sensor no longer detects the magnet as a first removaloccurrence; and then, within a defined second-time window aftercommencement of the first removal occurrence, moving the magnet backinto close proximity to the AIMD with the electronic circuitsregistering when the magnetic-detection sensor detects that the magnetis in close proximity to the AIMD as a second proximity occurrence,thereby causing the electronic circuits of the AIMD to enter intomagnet-mode.

The method according to the present invention further includesprogramming the electronic circuits to remain in magnet-mode uponcommencement of the second proximity occurrence for as long as themagnetic-detection sensor detects that the magnet is in close proximityto the AIMD, and providing the magnet having a strength of at leastabout 9 Gauss, and selecting the magnet-detection sensor from the groupof a reed switch, a Hall-effect sensor and a giant magnetoresistive(GMR) sensor.

Further, the method of the present invention includes programming theelectronic circuits so that the first-time window upon commencement ofthe first proximity occurrence has a duration of from 2 to 10 seconds,and so that the second-time window upon commencement of the firstremoval occurrence has a time duration of from 2 to 10 seconds.

An additional aspect of the present invention includes connecting theAIMD to a lead wire extending to a distal electrode in contact withbiological cells for providing the electrical therapy to the biologicalcells, then, within the defined second-time window after commencement ofthe first removal occurrence, moving the magnet back into closeproximity to the AIMD so that the magnetic-detection sensor againdetects that the magnet is in close proximity to the AIMD as a secondproximity occurrence, thereby causing the electronic circuits to enterinto magnet-mode so that the AIMD either discontinues providingelectrical therapy to the biological cells or enters into a presettherapy mode for providing electrical therapy to the biological cells,and further including programming the electronic circuits to remain inmagnet-mode upon commencement of the second proximity occurrence for aslong as the magnetic-detection sensor detects that the magnet is inclose proximity to the AIMD.

Another aspect of the present invention includes programming theelectronic circuits to register when the magnetic-detection sensordetects that the magnet has either a north or a south polarity facingthe AIMD as the first proximity occurrence, and then, within the definefirst-time window after commencement of the first proximity occurrence,removing the magnet from being in close proximity to the AIMD so thatthe magnet-detection circuits no longer register that the magnet is inclose proximity to the AIMD as the first removal occurrence, and then,within the defined second-time window after commencement of the firstremoval occurrence, flipping and moving the magnet into close proximityto the AIMD so that the magnet-detection sensor detects the other of thenorth and the south polarity of the magnet as the second proximityoccurrence, thereby causing the electronic circuits of the AIMD to enterinto magnet-mode, and further programming the electronic circuits toremain in magnet-mode upon commencement of the second proximityoccurrence for as long as the magnetic-detection sensor detects that themagnet is in close proximity to the AIMD.

An alternate method according to the present invention includesprogramming the electronic circuits not to enter into magnet-mode uponcommencement of the second proximity occurrence, further including:within a defined third-time window after commencement of the secondproximity occurrence, moving the magnet away from the AIMD so that themagnet-detection sensor no longer detects the magnet with the electroniccircuits having been programmed to register a second removal occurrence;and then, within a fourth-time window after commencement of the secondremoval occurrence, moving the magnet back into close proximity to theAIMD so that the magnet-detection sensor detects the magnet as a thirdproximity occurrence, thereby causing the electronic circuits of theAIMD to enter into magnet-mode, and programming the electronic circuitsto remain in magnet-mode upon commencement of the third proximityoccurrence for as long as the magnetic-detection sensor detects that themagnet is in close proximity to the AIMD or, programming the electroniccircuits not to enter into magnet-mode upon commencement of the secondproximity occurrence, so that within a defined second plus x-time windowafter commencement of the second proximity occurrence, moving the magnetaway from the AIMD so that the magnet-detection sensor no longer detectsthe magnet as a first plus x removal occurrence; and then, within asecond plus x+1-time window after commencement of the first plus xremoval occurrence, moving the magnet back into close proximity to theAIMD so that the magnetic-detection sensor detects the magnet as asecond plus x proximity occurrence, thereby causing the electroniccircuits of the AIMD to enter into magnet-mode, and programming theelectronic circuits to remain in magnet-mode after commencement of thesecond plus x proximity occurrence for as long as the magnetic-detectionsensor detects that the magnet is in close proximity to the AIMD.

These and other aspects of the present invention will becomeincreasingly more apparent to those of ordinary skill in the art byreference to the following detailed description and the appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a wire-formed diagram of a generic human body showing a numberof implanted medical devices.

FIG. 1A illustrates the relative size of a cardiac pacemaker withrespect to a U.S. penny (1-cent piece).

FIG. 1B illustrates the chest of a human patient with the outline of adual chamber ICD 100I implanted subcutaneously.

FIG. 1C shows a visible protruding lump in the patient's chest from theimplantation of a pacemaker 100C.

FIG. 1D illustrates a dual chamber cardiac pacemaker with its associatedleads and electrodes implanted into a human heart.

FIG. 1E illustrates a reed switch 202 in an open position and a closedposition.

FIG. 1F illustrates a bar magnet 208 being brought into relatively closeproximity to a Hall-effect sensor 209.

FIG. 1G illustrates a typical clinical magnet 210 that is used to placean AIMD, such as a pacemaker or ICD into magnet-mode.

FIG. 1H illustrates the south face of the magnet 210 shown in FIG. 1Gnext to a U.S. quarter 216 (25-cent piece) for size comparison.

FIG. 1I illustrates various donut-shaped or toroidal-shaped clinicalmagnets 210, 232, 234, 236, 238, 240 and 242 that are designed to causean AIMD to enter into its magnet-mode.

FIG. 1J shows the clinical magnet 210 of FIG. 1H in the hand of aclinician who is about ready to place it over the patient's AIMD.

FIG. 1K shows a clinician properly placing the clinical magnet 210 ofFIG. 1H over a patient's AIMD in a pectoral pocket area.

FIG. 1L shows the clinical magnet 210 of FIG. 1H being placed over aCIED, such as a cardiac pacemaker or ICD and an EKG electrode 216, whichis monitoring cardiac waveforms.

FIG. 1M illustrates that the patient shown in FIGS. 1J and 1K is innormal sinus rhythm 218 and after placement of the clinical magnet 210of FIG. 1H, asynchronous fixed-rate pacing 220 occurred.

FIG. 1N is a slide taken from a pacemaker manufacturer that illustrateswhat happens when a magnet is deliberately placed over a pacemaker.

FIG. 1O is an ICD magnet summary taken from a paper presented to theHeart Rhythm Society.

FIG. 2 is a is a side view of a human skull with two quadpolar brainstimulation electrodes placed deeply into brain matter.

FIG. 3 is an X-ray tracing of the front view of the pectoral area of thesame patient shown in FIG. 2 , showing two implantable deep brainstimulator pulse generators 26 and 26′.

FIG. 4 is a diagram showing how wireless cell phone charging works.

FIG. 5 is a is a diagrammatic representation of a base station 250wirelessly coupled to a power receiver 252.

FIG. 6 illustrates an iPhone 12's MAGSAFE charging puck 224 for aniPhone 12 230.

FIG. 7 is a photograph showing the back of the iPhone 12 with theMAGSAFE charging puck 224 shown in FIG. 6 magnetically adhered to thephone.

FIG. 8A is a CT scan showing that the ring magnet 232 of an iPhone® 12has a diameter that is a significant portion of the width of the phoneand similar to the diameter of a clinical magnet

FIG. 8B is a CT scan of an iPhone 13 showing that the phone has a ringmagnet that is very similar to the ring magnet of an iPhone 12.

FIG. 8C is a CT scan of an Apple watch showing that the watch has asolid rectangular magnetic.

FIG. 9 is a flow chart of one embodiment of the present invention.

FIG. 10 is a flow chart of another embodiment of the present inventioncalled the novel multi-flip magnet-mode 400.

FIG. 11 is a flow chart 410 of a two-flip embodiment or a double-flipmagnet-mode embodiment or an n-flip embodiment of the present invention.

FIG. 12 is a schematic view of a prior art cardiac pacemaker 100C havinga laser engraved skin target 418 for alignment of a magnet to place thepacemaker in magnet-mode.

FIG. 13 shows the pacemaker 100C of FIG. 12 with a donut magnet 210aligned with a dot 420 on the skin 422 of a patient to inducemagnet-mode for the pacemaker.

FIG. 14 is a schematic view showing that precise clockwise and thencounterclockwise rotation of a ring magnet 212 that can be used tosafely induce magnet-mode in an AIMD according to the present invention.

FIG. 15 is a schematic illustrating that magnet-mode in an AIMD can besafely induced by first applying a lower strength magnet 212′ and thenwithin a specific time period, applying a higher strength magnet 212″.

FIG. 16 is a flow chart 504 showing a typical application and timingsequence of alternate strength magnets to an AIMD as described in FIG.15 .

FIG. 17 is a perspective view of a strip magnet with various magnets M₁through M₅ that alternate from north to south to north.

FIG. 18 illustrates a modification to an iPhone 12 (or any otherportable electronic device that has a strong magnet) with the additionof a target 426.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Definition: time limitations or windows of each magnet placement over anAIMD or flip in the flow charts of the present invention are greaterthan one second but may be as long as hundreds of seconds. In apreferred embodiment, the time windows range from about 3 seconds toabout 10 seconds. In an alternate embodiment, the time windows rangefrom about 2 seconds to 20 about seconds. The clinical magnet placementtiming and the timing between flips does not need to be precise and cansimply embody the clinician counting in his head, or silently singingthe words “happy birthday to you”, and the like.

Turning now to the drawings, FIG. 1 is a wire-formed diagram of ageneric human body showing a number of implanted medical devices.Numerical designation 100A relates to a family of external andimplantable hearing devices which can include the group of hearing aids,cochlear implants, piezoelectric sound bridge transducers, and the like.

Numerical designation 100B includes an entire variety ofneurostimulators and brain stimulators. Neurostimulators are used tostimulate the Vagus nerve, for example, to treat epilepsy, obesity, anddepression. A brain stimulator is similar to a pacemaker-like device inthat it includes electrodes implanted deep into the brain for sensingthe onset of a seizure and also for providing electrical stimulation tobrain tissue to prevent a seizure from occurring. The leads that comefrom a deep brain stimulator are often placed using real time imaging.Most commonly such leads are placed during real time MRI imaging.

Numerical designation 100C relates to the family of cardiac pacemakers,which as is well-known in the art, may have endocardial or epicardialleads. Implantable pacemakers may also be leadless. The family ofcardiac pacemakers 100C includes a cardiac resynchronization therapydevice (CRT-D pacemakers) and a leadless pacemaker. A CRT-D pacemaker isunique in that it is designed to pace both the right and left sides ofthe heart. The family of cardiac pacemakers 100C also includes all typesof implantable loop recorders or biologic monitors, such as a cardiacmonitor. The illustrated cardiac pacemaker 100C could also be any typeof biologic monitoring or data recording device including looprecorders, and the like.

Numerical designation 100D includes the family of left ventricularassist devices (LVAD's) and artificial hearts.

Numerical designation 100E includes the entire family of drug pumps,which can be used for dispensing insulin, chemotherapy drugs, painmedications, and the like. Insulin pumps are evolving from passivedevices to active devices that have sensors and closed loop systems tomonitor blood sugar levels in real time. Active drug pumps tend to bemore sensitive to EMI than passive pumps that have no sense circuitry orexternally implanted leads.

Numerical designation 100F includes a variety of external or implantablebone growth stimulators for rapid healing of fractures.

Numerical designation 100G includes urinary incontinence devices.

Numerical designation 100H includes the family of pain relief spinalcord stimulators and anti-tremor stimulators. Numerical designation 100Halso includes an entire family of other types of neurostimulators usedto block pain.

Numerical designation 100I includes the families of implantablecardioverter defibrillator (ICD) devices and congestive heart failuredevices (CHF). These types of devices are known in the art as cardioresynchronization therapy devices, otherwise known as CRT devices.

Numerical designation 100J illustrates an externally worn pack thatcould be an external insulin pump, an external drug pump, an externalneurostimulator, a Holter monitor with skin electrodes or even aventricular assist device power pack.

It is noted that numerical designation 100I is illustrated as animplantable defibrillator, which can have either endocardial orepicardial leads. This family also includes subcutaneous defibrillators.

It is also noted that some of the medical devices depicted in FIG. 1 canhave both an implanted part and an externally worn part, such as thefamily of devices indicated with numerical designation 100J. Ofparticular concern from a human factor perspective are those implantedmedical devices that can be implanted in a pectoral pocket area. Theseinclude those with numerical designations 100B, 100C, 100D, 100I and100L.

Not shown in FIG. 1 is the human buttocks area, which is a common placeto implant a spinal cord stimulator. Other common locations forimplantation of AIMDs include the abdomen, or areas low in the groin.

FIG. 1B illustrates the chest of a human patient with the outline of adual chamber ICD 100I implanted subcutaneously (sub-Q), which is mosttypical. Implant depth is important as the static magnetic fieldstrength drops as an exponential function as the distance from theclinical magnet surface (or an inadvertent magnet) increases. Thin andelderly (thin skinned) patients with sub-Q implants are at the greatestrisk of inadvertent magnet-mode response because their AIMD implantdepth is typically relatively small (on the order of a few millimeters).Leads with distal electrodes are shown routed into endocardial tissue inthe human heart. When a subcutaneous implant is performed, the implantdepth from the skin surface is reduced. This makes the implanted devicemore susceptible to undesirably entering into magnet-mode when aportable electronic device, such as a cell phone with a chargingalignment magnet is placed over the device, for example, in a shirtpocket. For perspective, the cardiac pacemaker 1000 with leads is shownnext to a U.S. penny 201 in FIG. 1A.

FIG. 1C shows a visible protruding lump in the patient's chest from anolder version of an implanted cardiac pacemaker 100C. Modern pacemakersare much thinner, making the pectoral implant more comfortable for thepatient. However, a clinician can still palpitate the area and feel theoutline of the implanted pacemaker, which assists in deliberate placingof a pacemaker magnet. Spatial location of the magnet over the implantedpacemaker is important for activating magnet field sensors in thepacemaker or AIMD. Accurate spatial location over the implant isparticularly important when the implant depth is deep. Elderly pacemakerpatients, with a subcutaneous AIMD implant, generally have very thinskin, which means that the implant depth is not very deep. In that case,inadvertent AIMD magnet-mode entry, for example, by the ring magnet ofan iPhone 12 becomes more likely because the distance between the phoneand the subcutaneous implant is not very great (refer once again toTable 1). On the other extreme, a subpectoral muscle implant in a highbody mass index (BMI) patient can result in the implant depth beingseveral centimeters. In that situation, accurate spatial locationbecomes even more important.

FIG. 1D is taken from FIG. 6 of U.S. Pat. No. 10,561,837 and illustratesan AIMD, such as a cardiac pacemaker or ICD. The AIMD has a hermeticallysealed housing 124 supporting a plastic or Tecothane® header block 138into which leads 110 and 110′ are plugged into and routed transvenouslyto electrodes located within the heart 112. The AIMD active electroniccircuit board 130 is shown. It will be appreciated that this could beone circuit board or multiple circuit boards. Disposed on at least oneAIMD circuit board is a programmable microprocessor 131, which can alsobe thought of as a minicomputer.

Numerical designation 200 indicates a static magnetic field detectorsuch as a reed switch, a Hall-effect sensor or a GMR sensor. These arejust three examples of many types of static and/or time varying magneticfield sensors that may be used in AIMDs (or in the future may be). Thepresent invention also covers emergent or new technologies yet to bediscovered in the field of static magnetic field sensors. Importantly,the static magnetic field sensor at a minimum detects the presence of aclinical magnet and provides an output that can be used in new AIMDprogramming as describe herein. In a preferred embodiment, the AIMDmagnetic field sensor both detects the presence of a clinical magnet andalso its north-south or south-north polarity.

FIG. 1D is a pectoral view of a cardiac pacemaker 100C showing dualchamber bipolar leads 110, 110′ routed to distal tip electrodes 118 aand 118 b and distal ring electrode 120 a and 120 b. As can be seen, theleads 110, 110′ are exposed to a powerful RF-pulsed field from an MRImachine. This induces electromagnetic energy on the leads which arecoupled via ISO Standard IS-1 or DF-1 connectors 126 a/126 b, 128 a/128b through header block 138 which connect the leads to electroniccircuits supported on a circuit board 130 inside the hermetically sealeddevice housing 124. A hermetic seal assembly 132 is shown with a metalferrule 134 which is generally laser welded into the titanium housing124 of the cardiac pacemaker 100C. Lead wires 136 a through 136 dpenetrate the ferrule 134 of the hermetic seal in non-conductiverelation. Glass seals or gold brazed alumina insulators are formed tomake the hermetic seal which keeps body fluids from getting to theinside of the pacemaker housing 124. Also shown is a rectangularquadpolar feedthrough capacitor (planar array) 140 mounted to thehermetic terminal 132. All of the element numbers in FIG. 1D are thesame as the element numbers in U.S. Pat. No. 10,561,837, the contents ofwhich are herein incorporated fully by reference.

Referring once again to FIG. 1D, a static magnetic field sensor 200,such as a reed switch, a GMR sensor, a Hall-effect sensor,anisotropic/giant/tunnel magneto-resistance sensor is supported on thecircuit board 130 housed inside the AIMD. The magnetic field sensor isdesigned to sense the magnetic field when a clinical magnet is purposelyplaced over the device, for example, when it is desired to have thedevice enter into magnet-mode at a predetermined static magnetic fieldstrength.

FIG. 1E illustrates a typical reed switch 202 having internal mechanicalcontact plates and reed blades. Application of a magnet 208 directlyover the reed switch 202 causes contact 204 to close. When the magnet208′ is misaligned or not directly over the reed switch 202, however,the switch remains open 206. Today, some AIMDs still use a reed switch,but many now use Hall-effect or equivalent sensors 200, including thosethat are described in U.S. Pat. No. 8,600,505 (FIG. 1D).

A Hall-effect sensor 200 is a device used to measure the magnitude of amagnetic field. Its output voltage is directly proportional to themagnetic field strength through it. Frequently, a Hall-effect sensor iscombined with a threshold detector so that the sensor acts as a switch.When a Hall-effect sensor 200 acts as an electronic switch, there areimportant advantages. A Hall-effect switch costs much less than amechanical switch (including a Reed switch 202) and is much smaller andmore reliable. Further, a Hall-effect sensor operates at much higherfrequencies than a mechanical switch and because it is a solid-stateswitch, it typically does not suffer from contact bounce. TheHall-effect sensor 200 (FIG. 1D) can measure both the polarity andamplitude of a wide range of static magnetic fields (no current AIMDtakes advantage of this ability to sense polarity). The Hall-effectsensor 200 can have many shapes including flat. Additionally, a reedswitch 202 has a binary on/off threshold of some variability whereas aHall-effect sensor 200 produces a continuous output of excellentprecision and accuracy.

FIG. 1F illustrates a bar magnet 208A being brought into relativelyclose proximity to a Hall-effect sensor 200. At a predetermined level ofstatic magnetic field strength, circuitry in the Hall-effect sensor 200produces an output voltage which triggers other AIMD circuitry to entermagnet-mode. In general, this predetermined static magnetic fieldstrength level is programmable.

FIG. 1G illustrates a typical pacemaker or ICD magnet 210 in a donut ortoroidal shape. As an example, the magnet facing side is marked with thestatic magnetic polarity “north” 212. Clinical magnets do not havenorth-south labelling on them. The opposite side of the magnet 210,which cannot be seen, is marked with the static magnetic polarity“south” 214. The purpose of this magnet is to position it over an AIMDto place the AIMD into its magnet-mode (without regard to polarity).Generally, such existing clinical magnets 210 have a field strength ofabout 70 to 120 Gauss with a minimum field strength, in accordance withISO 14117, of 9 Gauss. The static magnetic field strength of a magnet,in Gauss, depends on whether the measurement is taken at the face of themagnet or some distance away from the face. This is why the reference toISO 14117, which has a specific method of measuring Gauss. ISO 14117specifies that a clinical magnet shall not induce magnet-mode at a fieldstrength less than 9 Gauss.

There are hundreds of thousands, if not millions, of these types ofclinical magnets scattered throughout the world from clinics (includingin third world countries) to major hospitals to emergency rooms. A majorpurpose of the present invention is to find an effective way to safelyuse these existing clinical magnets to activate the magnet-mode in anAIMD. Clinical magnets are not marked with a north or south polarity noris any commercially available AIMD enabled or programmed to detect thenorth-south polarity of a clinical magnet.

FIG. 1H illustrates the south face of the magnet 210 next to a U.S.quarter 216 (25-cent piece) for size comparison. FIG. 1H also describeswhat happens when a relatively strong magnet 210 is placed directly overa conventional pacemaker. As indicated, the magnet 210 will switch thepacemaker to an asynchronous magnet-mode. As previously discussed,prolonged asynchronous pacing can lead to reduced hemodynamic output,premature battery depletion, and a rare but very dangerous R-T event,which can induce immediate life-threatening ventricular fibrillation(VF).

FIG. 1I illustrates that clinical magnets 210, 232 designed to put anAIMD into magnet-mode can also be donut-shaped or toroidal, solid roundmagnets 234, square magnets 236 or even rectangular magnets 238. It willalso be appreciated that the magnets can even be elliptical with acenter hole or solid ellipses 242. In other words, the present inventionis not constrained by any particular magnet shape.

FIG. 1J shows the clinical magnet 210 in the hand H of a clinicianbefore placing the magnet over the patient's AIMD.

FIG. 1K shows the clinician properly placing the clinical magnet 210over a patient's AIMD that is implanted in a left-chest pectoral pocketarea.

FIG. 1L is a close-up of the magnet 210 being placed over the AIMD. Alsoshown is an EKG electrode 216, which is designed to monitor cardiacwaveforms.

FIG. 1M illustrates that this particular patient was in normal sinusrhythm 218 and after placement of the clinical magnet 210, asynchronouspacing 220 occurred. One can see that the patient is now experiencingcompetitive pacing where the pacemaker is causing the heart to beatasynchronously with the patient's normal sinus heart rhythm. Pacemakersare generally used to treat bradycardia (slow heart rate). If thispatient were in a bradycardic condition, that would mean the patient didnot have an underlying sinus rhythm and there would be no potential forrate competition. However, the vast majority of bradycardic patients arenot in bradycardia all the time. They may become bradycardic once ortwice a month or at certain times in a day. Consequently, prolonged andinadvertent placement of a strong magnet (for example, the iPhone 12ring magnet) can lead to the illustrated rate competition scenario 220.Unintended and prolonged rate competition is not healthy as the heartbeats with an out of synchronization chaotic rhythm.

FIG. 1N is a slide taken from a pacemaker manufacturer that illustrateswhat happens when a magnet is deliberately placed over a pacemaker. Oneof the bullet points says, “Caution: asynchronous rate may not alwaysmeet the physiologic demands of the patient.”

FIG. 1O is an ICD magnet summary taken from a paper presented to theHeart Rhythm Society. As one can see, there are variations inmagnet-mode between ICD manufacturers, but one thing is constant withevery manufacturer and that is in response to a deliberately placedmagnet—ICD high voltage shock therapy is inhibited until the magnet isremoved. As previously described, inadvertent suspension of high-voltagetherapy, particularly for a prolonged period of time, means that the ICDis not able to respond to a life-threatening arrhythmia, such asventricular fibrillation. In other words, life-saving high-voltage shocktherapy, in the presence of the magnet, is not possible.

FIGS. 2 and 3 are taken from FIGS. 1 and 2, respectively, of U.S. Pat.No. 8,792,987. The element numbers depicted on FIGS. 2 and 3 are takendirectly from the '987 patent, which is herein incorporated fully bythis reference. Referring first to FIG. 2 , one can see deep brainelectrodes 20 and 20′ that stimulate a particular area of the humanbrain to treat systems, such as Tourette's syndrome or Parkinson'sDisease. These deep brain devices may have a magnet-mode which in mostcases is used to suspend therapy (particularly during surgery when aclinical magnet is taped in place).

FIG. 3 indicates that the leads 22 and 22′, in this case, are tunneleddown to an implantable medical device or a deep brain stimulator (DBS),as shown on either the left or the right side (or both), in a pocketthat the surgeon creates in the pectoral area. In general, cardiacdevices, such as pacemakers and ICDs, and deep brain stimulator or evenVagus nerve stimulators (for epilepsy) can be implanted into thepectoral area either subcutaneously (meaning near the skin surface) orsubpectorally (which means under the pectoral muscle). The types ofimplants that would be most at risk for undesirable placement of amagnet over them would be ones that are implanted subcutaneously,otherwise known as sub-Q. That is because the implant is much closer,for example, to a cell phone placed in a shirt pocket. The staticmagnetic field from a fixed magnet drops or decreases as the distancefrom the magnet increases. So, close proximity to the implant is a majorconcern.

FIG. 4 is a diagram showing how wireless cell phone charging works. Atransmitter coil 236 generates a pulsing electromagnetic field. Forelectric vehicle charging, these are generally in the range of 15 to 25kilohertz. For wireless charging of a cell phone, this might be in therange of 80 to 300 kilohertz. The present invention is directed to amuch broader frequency range generally from 10 to 500 kilohertz. Thetransmitter coil 236 produces a pulsing electromagnetic field wherein aclosely spaced receiver coil 234 picks up this energy, similar to how atransformer works. The receiver coil 234 is disposed inside the activeimplantable medical device (AIMD) and the transmitter coil 236 isconnected to a charging wand, a charging puck 224 (FIGS. 6 and 7 ), acharging station, a charging desktop, and the like.

Importantly, the receiver coil 234 and the transmitter coil 236 need tobe tightly or strongly coupled. In other words, distance Z, which is thespacing between the receiver and transmitter coils 234, 236 must besmaller than D, which is the diameter of the coils. Optimal transmission(energy coupling) occurs when the transmitter coil 236 has the samegeometry and the same diameter as the receiver coil 234. The receivercoil 234 is generally connected to an electronic circuit that convertsthe AC signal that is received to a DC signal to thereby recharge thebattery of the portable electronic device, including a cell phone, suchas the iPhone 12 230. Optimal energy transfer occurs when thetransmitting coil 236 is spatially aligned with the receiver coil 234,which is one purpose of the magnet in devices such as the iPhone 12.Another purpose of the magnet is magnetic adherence to the charging puckor wand such as a MAGSAFE® charging device. (MAGSAFE is a registeredtrademark of Apple Inc., Cupertino, Calif.) Another purpose of themagnet in a portable electronic device, such as a cell phone, is so thatthe transmitting station can sense the magnet field and activate itself,in other words, start transmitting.

FIG. 5 is a diagrammatic representation of a base station 250 wirelesslycoupled to a power receiver 252, which can be a mobile device such as acellular phone. RF coupling is represented by facing coils 234, 236 ofthe base station 250 and the power receiver 252. Think of the basestation 250 as the desktop or the center console of an automobile or thewand/puck of the iPhone 12 that creates the pulsing electromagneticfield picked up by the secondary coil in the power receiver (iPhone 12)in the mobile or portable device, such as a cellular phone.

FIG. 6 illustrates an iPhone 12's MAGSAFE® charging puck or wand 224.Inside this charging puck 224 is the transmitting coil 236 for wirelesscharging. The charging puck 224 has wires 226 shown at the bottom, whichmust be connected to an energy source (the base station 250 such asshown in FIG. 5 ). The base station 250 is connected to an energysource, for example, an AC wall plug or a box that plugs into a wallplug with a USB jack. With this MAGSAFE® wireless charging system, thereis no need for any wires to be connected directly to the iPhone 12 torecharge its internal battery (this is why it is called wirelesscharging). The charging puck 224 has an embedded transmitting coil 236,as previously described in FIG. 4 .

FIG. 7 shows an iPhone 12 with the MAGSAFE charging puck 224magnetically adhering to the back of the phone. Importantly, for maximumand efficient wireless charging and energy transfer, it is desirablethat the transmitter coil 236 and the receiver coil 234 be spatiallyaligned as shown in FIG. 4 . When the receiver coil 234 is significantlyoff-center from the transmitter coil 236, energy transfer issignificantly reduced. Then little to no energy is transferred and thebattery of the portable or body worn device will either be chargedinefficiently or not charged at all. Referring to FIGS. 8A and 8B, thereis a ring magnet 232 inside of the iPhone 12 and iPhone 13 thatcorresponds either to the magnet or a ring steel plate in the chargingpuck 224 so that the transmitter coil 234 and receiver coil 236 (FIG. 5) are magnetically adhered and spatially aligned.

Referring now to FIGS. 8A, 8B and 8C, high-resolution computerizedtomography (CT) scans of an iPhone 12, iPhone 13 and an Apple watch,respectively, were obtained so that their circuits, magnets and coilscould be clearly and accurately visualized. FIGS. 8A and 8B show thatthe ring magnet 232 of the iPhone 12 and iPhone 13 have a diameter thatis a significant portion of the width of the phone. Such a ring magnet232 helps the iPhone 12 and iPhone 13 adhere and spatially align itsreceiver coil 234 with a transmitter coil 236. The transmitter coil 236is ideally centered within the ring magnet. Unfortunately, such a largediameter ring magnet can create a large “sweet spot” over an implantedAMID magnet field sensor, which can enable prolonged inadvertent magnetmode response, which can be dangerous.

FIG. 8B is a high-resolution CT scan of an iPhone 13 showing that italso has a ring magnet similar to the iPhone 12. In the case of theiPhone 13, the ring magnet appears to be even larger in diameter thanthe ring magnet of the iPhone 12.

FIG. 8C illustrates a powerful (refer again to Table 1) solidrectangular magnet inside the back of an Apple watch to facilitatespatial alignment and magnetic adherence to a base station or a chargingpuck 224.

In that respect, the present invention describes a new programmingmethod using AIMD microprocessor firmware or software for inducing anAIMD into magnet-mode. These AIMD apparatus changes match a new clinicalmagnet mode application method. For most existing AIMDs, this can beaccomplished through software upgrades or patches. For other AIMDs,hardware upgrades may be required.

In a first embodiment (FIG. 9 ), multiple placements of a clinical donutor equivalent magnet 210 over the AIMD magnetic field sensor (such as aHall-effect, reed switch or a GMR sensor 200) (FIGS. 1H to 1K) includinga deliberate time sequence are required to significantly reduce thechance of an inadvertent induction of magnet-mode. In a secondembodiment (FIG. 10 ), multiple AIMD detected north-south or south-northflips of a magnet are required to induce magnet-mode. For theembodiments of FIG. 9 or 10 to reliably work in the clinicalenvironment, clinicians must be taught the new universal clinical magnetplacement sequence method shown in the flow chart illustrated FIG. 11(this new clinical method is compatible with either multiple placementsor multiple placements with magnet flips in between).

For example, it is highly unlikely that an iPhone 12 will be removed andreplaced in a shirt pocket several times in a row, each time reversingthe orientation of the magnet contained in the phone. On the other hand,clinicians can be trained, for example, to do a “triple-flip”. With atriple-flip, the clinical magnet is placed with one side down and then,within a time period, such as 10 seconds, as one possible example,flipped over again, within seconds, flipped over again, and then lastly,flipped over a third time. The Hall-effect sensor 200 inside the medicaldevice detects these flips from north to south or south to north andcounts and time-sequence them such that it is only after the prescribednumber of flips and interim time windows that the medical device entersinto magnet-mode.

An alternative to this precise flip programming, is, if the clinicianmakes a mistake (misses the timing in one of the steps) and the AIMDdoes not enter magnet-mode at the last step, then the AIMD could beprogrammed to count an extra flip or even “x” extra flips to still entermagnet-mode (this few seconds of grace is an embodiment of the presentinvention, however, its implementation will be subject to discussionsand determinations within the societies of the medical community).

FIGS. 9, 10 and 11 illustrate AIMD software or firmware logic and methodflow charts of the present invention in which the number “x” (which canbe any number from 2 to 100) is shown in the last logic step box 308,408 or 416, respectively. The number “x” is defined herein as being thenumber of added steps after respective steps 306, 406 and 414 to theflow charts of FIGS. 9, 10 and 11 . Illustrative examples of “x” will begiven. It will also be appreciated that “x” can even be a negativenumber in some of the flow charts, meaning that a step is removed fromthe depicted sequence. In the present invention, there are always atleast two placements and when a flip is being detected, at least oneflip.

Also, with reference to FIGS. 9, 10 and 11 , as defined herein, theletters n₁, n₂, n₃ and n₄ each represent a specified magnetminimum/maximum application or minimum/maximum magnet removal timeperiod or window in seconds which can be any amount but in an embodimentvaries generally from 1 second to 100 seconds. As defined herein, n₂must always be greater than n₁, and n₄ must be greater than n₃, etc.When the subscript of “x” is an odd number (1, 3, 5 . . . ), then “x” isa minimum time placement in seconds. When the subscript of “x” is aneven number (2, 4, 6 . . . ), then “x” is a maximum time number inseconds.

As a simple example using a single flip: there is a first magnetplacement in close proximity to the AIMD of no less than n₁ seconds andno greater than n₂ seconds. Then, the magnet must be removed from beingin close proximity to the AIMD within the n₁ to n₂ time window. Then,the magnet is flipped once or not flipped and placed back into closeproximity to the AIMD in no less than n₃ seconds and no greater than n₄seconds, which results in the AIMD entering magnet-mode.

FIG. 9 illustrates a flow chart of one embodiment of the presentinvention. This is known as the novel no flip magnet-mode 300. At asummary level, a clinical magnet is first placed in close proximity tothe AIMD in step 302, the magnet is then removed from being in closeproximity to the AIMD and then placed again in close proximity to theAIMD in second step 304. The magnet is then removed from being in closeproximity to the AIMD and again placed in close proximity to the AIMD inthe third step 306. When the number “x” in the last step 308 equals one(1) additional step, four magnet placements are performed before theAIMD enters into magnet-mode if and only if each placement and removalfall within a prescribed time sequence or window. If x=2, two additionalplacements and removals after step 306 are performed for a total of fiveplacements of the magnet in close proximity to the AIMD. Thus, when x=1in FIG. 9 , there are four total placements. However, it will beappreciated that step 308 can be eliminated resulting in three magnetplacements in close proximity to the AIMD, or both steps 308 and 306 canbe eliminated resulting two magnet placements in close proximity to theAIMD before the AIMD enters into magnet-mode. If the goal is to keep anAIMD from inadvertently entering into magnet-mode, the preferredembodiment of the present invention is a minimum of four placements asillustrated when x=1 as illustrated in FIG. 9 . In the presentinvention, “x” placements can be any number greater than or equal to 2.Referring to FIG. 10 , which is the flip flow chart, it will beappreciated that the minimum number of flips is 1, meaning that thenumber of placements, in this case is two.

In step 302 of FIG. 9 , the clinical magnet is first placed in closeproximity to the AIMD. This activates the AIMD microprocessorprogramming logic which counts each placement, and when the logictotalizer reaches the specified number of correct placements within thecorrect time limits or time windows, it sends a signal or code withinthe AIMD circuitry to place the AIMD into magnet-mode. Operating in eachstep will be IF-THEN programming logic which will only produce a YESresponse in each step if the clinical magnet has been properly placed inno less than “n₁” seconds but no greater than “n₂” seconds. The IF-THENlogic counts the same or a different requirement for placement time andmagnet removal and then placement time. In other words, magnet removaltime and re-placement can be specified for no less than n₁ and n₃seconds and no greater than n₂ and n₄ seconds. In an embodiment, forsimplicity for the clinician to remember, n₁ seconds would equal n₃seconds and n₂ seconds would equal n₄ seconds. For example, place themagnet over the AIMD implant each time for between 2 to 10 seconds,remove the magnet from being in close proximity to the AIMD, flip themagnet in no less than 2 seconds and no more than 10 seconds and thenreplace the magnet over the AIMD implant again.

There are many types of static magnet field sensors with a Hall-effectsensor, a reed switch and a GMR sensor being exemplary, but which do notlimit the scope of the present invention. Stated simply, the programminglogic of FIGS. 9 and 10 should be compatible with almost all types ofmagnetic field sensors that are sensitive enough to produce an outputthat can be used as an input to programming logic. Swiping or movementof the magnet 210 during these placements is contraindicated in thebasic embodiments. Placing a dot or dots on the patient's skin with amarker pen would help the clinician to very accurately place the magnet210 in the same location after each flip or placement. If the AIMDsenses the magnet for a specified period of time along with a sufficientstatic magnetic detected field intensity, the microprocessor orequivalent logic circuitry of the AIMD produces a YES response, whichleads to removal to a suitable distance and the next magnet placement304 for a specified time.

For example, in step 302 of FIG. 9 , the magnet must be applied and thenremoved from being in close proximity to the device to a distance of atleast about 15 cm (about 6 in.), within a certain number of seconds, forexample, 2 to 10 seconds. The preferred removal distance is about 15 cm(about 6 inches) which includes a wide margin for error. In allembodiments of the present invention, the magnet 210 removal distance isat least 1 cm from the skin surface over the AIMD implant location.Then, the magnet 210 must be reapplied within this same time window instep 304 of FIG. 9 . If the magnet 210 is properly reapplied a secondtime in the specified time window, then in step 304, a YES response iscreated, which leads to step 306. Again, within the same time window(such as 2 seconds minimum to 10 seconds maximum), the magnet 210 isagain removed and then reapplied a third time in close proximity to thedevice. Each magnet application and removal sequence is defined hereinas one magnet iteration. This produces a YES response in step 306 inFIG. 9 . Step 308 in FIG. 9 shows that any number “x” of removals andreapplications (iterations) can be specified and programmed into theAIMD's computer logic.

In box 308, “x” can even be a negative number, such as −2, with twoboxes 306 and 308 being eliminated or subtracted from the magnetplacement and removal sequence. In that case, the total number ofplacements is 2, namely two magnet placements indicated by boxes 302 and304 with an interim removal. This is the most fundamental aspect of thepresent invention in order for an AIMD to enter into magnet-mode in step310. In that respect, step 304 is the final magnet placement step whenx=−2.

Regardless the value of “x” in the last step, upon performing the lastmagnet placement, the AIMD remains in magnet mode for as long as themagnet is in close proximity to the AIMD (for example, taped in place).So, in all embodiments, whether they be placements or flips, the laststep does not embody a minimum and maximum time window for a removal, asa removal can be from seconds to hours or even days. The AIMD will stayin magnet-mode for as long as the magnet 210 remains in close proximityto the implanted AIMD magnet field sensor. The magnet 210 can be tapeddown, for example, during surgery, to suspend therapy. If any of thesetiming sequences and placements are not done correctly (for example, theclinician drops the magnet), this results in a NO response, and the AIMDdoes not enter magnet-mode in step 310 in FIGS. 9, 10 and 11 . After apredetermined time-out period (for example, ten seconds), the cliniciancan start again from the top of the FIGS. 9, 10 and 11 flow chart andrepeat the sequence.

Referring once again to FIG. 9 , a timer or a clock 424 is indicated.However, the clock is not generally necessary, for example, for anapproximate timed magnet application and removal sequence (for example,as 3 seconds). All a clinician has to do is remember the number ofplacements and possible flips and count or sing a line from a tunebetween each removal and replacement of the clinical magnet. There is atradeoff between the time precision of placement and removal and agreater immunity against inadvertent entry into magnet-mode caused by aportable device or toy with a strong magnet. For example, a requirementfor magnet placement of 5 seconds, plus or minus 1 second, followed by aremoval of 3 seconds, plus or minus 1 second, would be more difficult,requiring the clinician to watch something like a digital timer. Such atightly controlled time sequence would have high immunity to inadvertentmagnet-mode entry but is more difficult to implement in practice(particularly in an emergency where rapid magnet placement is required).

The inventors expect that the international Heart Rhythm Society (HRS)in conjunction with the international neurostimulator society (NANS)will work together to determine suitable time sequences. HRS hasrequested prototypes for testing to assess the human factors and ease ofperforming the sequences. Ultimately, it will be the responsibility ofthe ISO 14708-1 working group to standardize a universal clinical magnettiming sequence for all AIMDs. Each AIMD type can have a differentsequence, for example, life sustaining CIED or AIMD devices likepacemakers and ICDs might require four or five magnet placements. But,for a spinal cord pain stimulator (which prevents pain but is not lifesustaining), two total placements might suffice. Deep brain implants canbe considered life sustaining when the patient is driving a car and thelike as inadvertent magnet-mode entry could suspend device therapyresulting in erratic and uncontrolled movements.

In an optional embodiment, the steps of FIG. 9 can have the addedrequirement that the static field reed switch or Hall-effect sensor 200does not produce a YES response unless a predetermined static magneticfield strength is also achieved during each placement of the clinicalmagnet. This requires repeated accurate spatial positioning in eachmagnet placements. AIMD implant depth, patient body mass index and skinthickness (related to age) are important variables. This is why clinicalmagnets are usually much stronger than 9 Gauss.

Providing a skin locating dot or even a permanent tattoo dot or mark asdescribed herein would greatly assist positional accuracy. Such accuratepositional placement enables yet another alternative embodiment whereinthe sensed magnetic field intensity of each magnet placement can have anupper and lower limit. This would additionally limit AIMD inadvertententry into magnet-mode, for example, from an iPhone®moving/sliding/swiping around in a shirt pocket.

In any of the embodiments of the present invention, the ISO 14117 10Gauss (1 mT) limit could also be significantly raised, for example, to500 Gauss or even higher. However, this is not an embodiment of thepresent invention as this requires that most clinical magnets 210 aroundthe world be replaced with much more powerful magnets. In combinationwith this, AIMD Hall-effect sensors 200 would need to be re-programmedsuch that they do not trigger below these new higher ISO 14117 levels.Powerful magnets of 500 Gauss or higher will make it less likely that aportable magnet in a device or toy can inadvertently induce AIMDmagnet-mode, however, such powerful magnets become very impractical inmany ways in that they will attract other objects and even be quitedifficult to pry off of a filing cabinet, and the like. There is no U.S.agency that regulates the strength of a static magnet that a portabledevice or toy may incorporate, so the idea that nothing more powerfulthan 500 Gauss will show up is also flawed (reference the Nikken 1 Powerchip Medallion Charm manufactured by Kenco which may be attached to alanyard worn around the neck or placed over any body area). Aspreviously stated, the Nikken 1 advertises a magnetic field strength of900-1000 Gauss.

In the present invention, and as described in FIGS. 10 and 11 , when themagnet 210 is removed or flipped, it must be removed at a suitabledistance from the AIMD such that the magnetic field sensor, for examplethe Hall-effect sensor 200, cannot trigger. A very conservative distancefor this purpose is about 15 centimeters (about 6 inches), but it couldbe closer. In the present invention, removal and flipping the magnet 210is described as any distance from about 1 to about 30 centimeters orgreater, with about 15 cm being the preferred distance.

FIG. 10 is a flow chart of another embodiment of the present inventioncalled the novel multi-flip magnet-mode 400. This is different than themagnet-mode described in FIG. 9 , where it was not necessary to flip themagnet 210 between placements. Clinical magnets are generally not markedwith north or south on their faces (so clinicians do not know which faceof the magnet is north or south).

To enable the multi-flip magnet-mode 400 of FIG. 10 , the AIMDHall-effect sensor 200 would first be programmed to detect magneticfield polarity as well as intensity (a reed switch cannot detectpolarity). Moving down the flow chart, in the first placement in step402, a donut magnet 210 is placed over the AIMD. It does not matter inthis first step whether the magnet 210 is placed on the patient's skinover the AIMD in either a north or a south polarity. The Hall-effectsensor 200 and its associated programming circuits will simply detectthat a magnet of suitable strength appeared and note that the magnet wasof a particular polarity, for example, a north polarity. Importantly, inthe second step 404, after the magnet 210 is properly removed within thetime sequence or time window of 402, the clinician flips the magnet 210over and places it again over the AIMD. This reverses the magnetic fieldpolarity, for example, from north to south or south to north. A YESresponse in the second step 404 means that within a specified timeinterval, for example, 5 seconds, the magnet 210 was removed, flippedover and then placed down again over the AIMD in a third placement step406. The clinical magnet is then removed, flipped and placed again in afourth placement step, as shown in block 408. And, if this sequence isdone within the correct minimum and maximum time windows, a YES responseis elicited and the AIMD enters magnet-mode. In this case, with theadded number of steps x=1, then step 408 becomes the final step and theAIMD remains in magnet-mode for as long as the clinical magnet is inclose proximity over the implant. It is appreciated that any number of“x” additional flips and placements can be specified in box 408.

In an embodiment related to the flow chart shown in FIG. 10 , x can be−1, meaning that step 406 is removed from the sequence. However, theleast number of flips allowed in the present invention is 1 between afirst and a second placement of the clinical magnet over an AIMD. For“The Triple Flip” embodiment of the present invention, x in box 408 isequal to +1, indicating one more removal, flip and placements after step406.

For example, a placement 402 followed by a triple flip would be easy toremember, wherein one places the magnet over the AIMD and then within 10seconds, flips it over, and then within 5 seconds, flips it over againand then within 5 seconds, places the magnet back over the AIMD afterthe third flip (the 5 second window or period is just an example, whichcan be changed to any specified time sequence). In general, theapplication times and removal and flip and reapplication durations allhave minimum and maximum limits. These time limits or time windows areimportant to prevent a portable device, such as a portable electronicdevice, like the iPhone 12, from being inadvertently flipped to triggermagnet-mode. It becomes highly unlikely either for FIG. 9 (the placementmethod) or FIG. 10 (the placement plus flip method) that the specifictime windows would happen inadvertently using an iPhone, and the like.

In any of the embodiments of the present application, one could changethe time duration or time sequence from one magnet application toanother, for example, 3 seconds, 5 seconds, 10 seconds, etc., to causethe AIMD to enter its magnet-mode 310.

Referring once again to FIG. 10 , “The Triple Flip” version of themulti-flip flow chart occurs when (x) in step 408 equals 1 additionalstep after step 406 (step 408 then becomes the third and final flip).This means that in step 408, there is no time window in which the magnetmust be removed. As long as the magnet is held in close proximity to theAIMD, the AIMD stays in magnet-mode.

Some AIMD manufacturers may want to put a maximum time limit onmagnet-mode. For example, they may want to terminate magnet-mode afterone hour to prevent too long a period of asynchronous pacing. That ispart of magnet-mode and not part of the present invention. So, themagnet-mode itself, and what therapy or lack of therapy the devicedelivers during magnet-mode is outside the scope of the presentinvention, including how long the device stays in magnet-mode before ittimes-out. Most AIMDs that the inventors are aware of will likely nothave a maximum time limit and instead, will stay in magnet-mode for aslong as the magnet is placed properly over the AIMD.

Still referring to FIG. 10 , for “The Triple Flip” embodiment, theclinical magnet 210 is first placed on the patient's skin over the AIMDwith any polarity in step 402 (the AIMD circuit logic records a firstYES response), then, for example, within two to ten seconds (an exampleof a tolerance), the magnet is removed and flipped over within aspecified time tolerance (the 1^(st) flip is recorded by the AIMD'slogic)), and then placed near or adjacent to the patient's skin over theAIMD a second time for a specified time tolerance or time window “n” instep 404 (the AIMD circuit logic records a second YES response), thenthe magnet is removed and flipped over within a specified time toleranceor time window (the 2^(nd) flip) and again placed over the AIMD in step406 (the AIMD circuit logic records a third YES response), and thenwithin another time tolerance or time window, the magnet 210 is removedand flipped over again (the 3^(rd) and final flip) in step 408 (and theAIMD logic circuits detect and record a fourth YES response). Incompleting step 408 (three flips) properly according to the abovesequence and time tolerances (without any NO responses), the AIMD entersits magnet-mode in step 310. The AIMD will stay in magnet-mode for aslong as the clinical magnet is kept/held in place over the AIMD (forexample, taped down over the AIMD implant).

If any of these steps are done incorrectly or not within the proper timesequence or time window, a NO response means that the AIMD does notenter magnet-mode (step 312).

“The Triple Flip” described above is one preferred embodiment of thepresent invention because:

1. It has a sufficient number of flips so that inadvertently flipping anexemplary iPhone or a child's toy in the same manner and timing becomehighly unlikely.

2. The term “Triple Flip” is catchy and easy for clinicians to remember.

3. Co-inventor Robert Stevenson's wife Wendy was the U.S. NationalGymnastics champion in 1976 and slated to be a member of the U.S.Olympics Team (she was injured just before the competition). Herspecialty was floor exercises and, in particular, “The Triple Flip.”

Again, the objective of the present invention is to make it highlyunlikely that a powerful magnet in a portable device, such as the iPhone12 or iPhone 13 would be flipped over in such a sequence that the ringmagnet 232 in the phone causes the AIMD to inadvertently orinappropriately enter magnet-mode.

FIG. 11 describes a universal AIMD clinical magnet placement method. Thereason this is called a universal method is that it captures the novelno flip magnet-mode depicted in FIG. 9 and also the novel multi-flipmagnet-mode depicted in FIG. 10 .

Referring to FIG. 11 , it is not important that the clinician know whichside of the magnet is north or south or how the AIMD is programmed. Inthe first magnet placement in step 412, the clinician simply places themagnet on or adjacent to the skin (for example, over a bandage) over theAIMD implant. During the placement 412, there is a specified time periodor window with a minimum and maximum time that the clinical magnet mustbe placed in close proximity over the AIMD device. Then, in the secondstep 414 and within a specific minimum and maximum time sequence or timewindow, the clinical magnet is removed to a suitable distance so thatthe AIMD no longer detects the magnet, for example, to about 15 cm, themagnet is flipped and then placed back down in its original positionover the AIMD implant. This constitutes the first flip. In the thirdstep 416, since placement of the magnet in step 414 occurs within theproper minimum and maximum time window, the AIMD enters magnet-mode. Inthis example, “x” in box 416 is equal to zero, meaning there isn't anadditional placement of the magnet over the AIMD after step 414.However, when x=1, there is one additional step of removing, flippingand placing again, within a minimum and maximum time window after step414, and this then becomes “The Triple Flip”.

Still referring to FIG. 11 , flips have been descried as part of auniversal magnet mode. However, the AIMD may or may not be detectingthese flips. This all depends on the type of static magnetic fieldsensor that the AIMD has. For example, if the AIMD has a reed switch,the placements would be counted and totaled before the AIMD enters intomagnet-mode. For some AIMDs, for example, those with a programmedHall-effect sensor, placements and flips of the clinical magnet are bothcounted, which gives a higher level of security against inadvertentmagnet-mode entry. It is not important that the clinician know whetherthe AIMD is counting the flips, or not. However, it is important thatthe clinician apply and flip the magnet as described in flow chart FIG.11 so that both cases are covered.

Referring back to FIG. 9 , where the AIMD is not programmed to sensenorth and south placements, the AIMD, which may have a reed switch,counts the number of placements within the prescribed time periods andif every step of the sequence is done correctly, there is a YES responseand in step 310, the AIMD enters magnet-mode. Referring once again toFIG. 11 , for an AIMD, for example, with a Hall-effect sensor that isreprogrammed to sense and count polarity reversals, each flip andplacement of clinical magnet over the implanted AIMD is counted/recordedby the software, and when “n”=1 in step 416, “The Triple Flip” has beenperformed, which elicits a YES response, thereby placing the AIMD intomagnet-mode in step 310.

According to the present invention, it is believed that the tripleplacements (FIG. 10 ) or “The Triple Flip” (FIG. 11 ) sequence of stepsis sufficient to prevent inadvertent activation from magnets containedin portable electronic devices or even in children's toys, and like.FIGS. 10 and 11 describe programming and even hardware design changes toAIMDs. The logic diagrams of FIGS. 10 and 11 are part of AIMD newhardware sensing and new/revised AIMD software logic where each YES orNO response is part of an If—Then type of software control flowresponse. In computer science, conditionals (that is, conditionalstatements, conditional expressions and conditional constructs) areprogramming language commands for handling decisions. Specifically,conditionals perform different computations or actions depending onwhether a programmer-defined Boolean condition evaluates to true (YES)or false (NO). In terms of control flow, the decision is always achievedby selectively altering the control flow based on some condition (apartfrom the case of branch predication). In the present invention,magnet-mode is entered only after the number of prescribed YES responsesoccur within the specified time windows. It will be up to variousmedical societies, including Heart Rhythm Society and perhaps NANS, andeven ISO to decide just how many placements/flips and the timingsequences that will be appropriate.

FIG. 12 is a schematic view of a cardiac pacemaker 1000, as previouslydepicted in FIG. 1 . The pacemaker 1000 has a header block 138 intowhich cardiac leads 110 and 110′ are plugged. There is a laser engravedtarget 418 which can be a circle within a circle or a circle with crosshairs or any other ISO adopted symbol. The purpose of this laserengraved marking on the outside of the pacemaker housing is to show theimplanting physician exactly where the reed switch or Hall-effect sensor200 (or equivalent) is located inside the hermetically sealed AIMDhousing 124. The AIMD magnetic field sensor 200 typically is located ona circuit board 130 (FIG. 1D) and may not be centered in the AIMDhousing as shown in FIG. 12 (it is often off to the side). By knowingthe magnetic field sensor location, the implanting physician duringsurgically building or closing the AIMD implant pocket can now affix atattoo or permanent ink dot or mark on the patient's skin directly overthe magnet field sensor 200. Such a mark or dot helps to enable thepresent invention where repeated placements or flips of a toroidalclinical magnet is required for the AIMD to properly enter magnet-mode.

FIG. 13 shows the pacemaker 1000 of FIG. 12 implanted in the human body.Spatially located over the pacemaker 1000 is a typical donut-shapedmagnet 210, which is intended to induce magnet-mode. A permanent dot 420or a temporary (surgical pen) mark 422 is shown on the skin of thepatient. This is to facilitate the present invention such that with eachremoval and reapplication of the magnet 210 of the AIMD, or in otherembodiments, each flip of the magnet, the magnet is centered over theAIMD at approximately the same location. This aspect of the presentinvention, therefore, prevents inadvertent swiping of the magnet. Theskin mark 420, 422 can be a small tattoo dot or permanent ink dot thatis applied at the time of implantation and spatially aligned with thetarget 418 that was laser engraved on the pacemaker housing 124. Theclinician can also take a surgical marking pen or even a sharpie andplace a dot on the patient's skin after palpitating and feeling theoutline of the pacemaker 1000. In the case where the magnet 210 is notdonut-shaped or has a solid core, it is appreciated that two or threemarkings around its outside circumference or perimeter can be applied tothe patient's skin either permanently or temporarily. The featuresillustrated in FIGS. 12 and 13 are optional embodiments of the presentinvention.

FIG. 14 illustrates that precise clockwise and then counterclockwiserotation of a ring magnet 212 could also be used to safely inducemagnet-mode. A disk/toroidal or cylindrical magnet 212 can be magnetizedin the axial direction (i.e., one flat side is north, the other flatside is south) or diametrically (i.e., one half of the curved side isnorth, the other curved side is south.) Therefore while FIGS. 10 and 11demonstrate a series of polarity inversions introduced by flipping themagnet side touching or near the patient's skin, the polarity inversiontechnique can also be sensed by a three-axis Hall-effect sensor 200 byrotating the magnet 212, for example, in 90° to 180° increments. In thatmanner, each incremental rotation achieves the same relative polarityinversion accomplished by a magnet flip.

Referring once again to FIG. 14 , the toroidal or donut ring magnet 212has been separated into a north half 502 a and a south half 502 b. Thisis different than the previously described conventional ring- ordonut-shaped magnet 210 that has north on the top and south on thebottom. By turning magnet 212 fully (or partially) clockwise and thenfully (or partially) counterclockwise and then fully clockwise again,the Hall-effect sensor 200 can be programmed to sense alternating southand north fields. However, this technique requires replacing allclinical magnets throughout the world with the illustrated bifurcatedmagnet 212, but is, nonetheless, a safe and effective way of having anAIMD entering magnet-mode. This technique also makes it highly unlikelythat a magnetic emitter, such as an iPhone 12 in a shirt pocket, willinadvertently or inappropriately cause an AIMD to enter intomagnet-mode. In summary, FIG. 14 represents an alternative embodiment ofthe present invention.

FIG. 15 is a schematic illustrating that magnet-mode in an AIMD can besafely induced by first applying a lower strength magnet 212′ and thenwithin a specific time period, applying a higher strength magnet 212″.Again, any number of sequences, including “n” sequences, of a weaker andstronger magnet could be used to assure that inadvertent movement of aniPhone 12 in a shirt pocket, and the like, will not induce magnet-modein an AIMD. Referring once again to FIG. 15 , this drawing shows thatthe smaller donut-shaped magnet 212′ uses a static magnetic fieldstrength of X Gauss and the larger, more powerful magnet 212″ produces astatic magnetic field strength of Y Gauss. In one embodiment, theclinical magnet has a strength that is between about 80 Gauss and 200Gauss. It is appreciated that the magnets 212′ and 212″ of FIG. 15 canbe the same size and shape. However, providing them of different sizeshelps the clinician ascertain which of the two magnets has a strongermagnetic field than the other.

FIG. 16 shows a block diagram 504 of a typical application and timingsequence of alternate strength magnets 212′ and 212″ shown in FIG. 15 .In first step 506, the X Gauss 212′ magnet is placed over the AIMD andthen within a specific time interval or time window, it is removed at asuitable distance (for example, more than 6 inches). Then, a differentmagnet of Y Gauss 212″ is repositioned over the AIMD in a second step508. Then again, within a specific time sequence or time window, the YGauss magnet 212″ is removed, and the lower strength X Gauss magnet 212′is applied over the AIMD in step 510. As before, the YES response in thethird step 510 can be repeated any number of “n” additional times 512(where “n” is greater than 1 and less than 100). If all of these stepsare done correctly, the AIMD will enter its designed magnet-mode in step310. Of course, this process requires the use of two different strengthmagnets 212′ and 212″ that must be properly labeled and distributedworldwide.

FIG. 17 illustrates a strip magnet 600 with various magnets M₁ throughM₅ that alternate from north to south to north. The strip magnet 600 canhave any number of magnetic sections 602, 604, 606, 608 and 610 and issimilar to a magnetic door lock. In this embodiment, the bar magnet 600is swiped over the AIMD, which causes the Hall-effect sensor 200 todetect within the swipe period the number of polarity reversals andwhether those polarity reversals are in the programmed sequence neededto cause the AIMD to enter magnet-mode. It is appreciated that anymagnetic sequence with the bar magnet 600 can be programmed into theAIMD's logic, for example, north-north-south-south. Bar magnet 600 canhave any number of north or south segments generally between 2 and 20.Again, the bar magnet 600 of FIG. 17 requires replacing all of theclinical donut-shaped magnets in use throughout the world. Additionalembodiments using the bar magnet 600 can include partial rotations asrepresented in FIG. 16 , but not full polarity inversions.

FIG. 18 Illustrates a modification of the iPhone 12 (or any otherportable electronic device that has a strong magnet) with the additionof a target 426. As shown, this could be a painted-on circle orimprinted circle with cross hairs, or any other target that is part ofan ISO Standard. This modification is intended to change an iPhone 12 sothat it can be used in an emergency as a deliberately applied clinicalmagnet. For example, referring once again to FIG. 9 , instead of usingthe donut-shaped magnet 210, the iPhone 12 can replace the magnet 210and be used as described for the no flip magnet-mode 300 technique forplacing an AIMD in magnet-mode. In other words, ring magnets such asthose in the iPhone 12, with a proper timing sequence, can be used by apatient or even a clinician to deliberately induce magnet-mode. This canresult in the iPhone 12, and the like, being taped down over the implantin an emergency to keep magnet-mode properly induced. In that respect,the iPhone 12, iPhone 13, Apple watch and similar portable electronicdevices with a strong magnet can be used with the no flip techniqueillustrated in FIG. 9 , or the multi-flip techniques of FIGS. 10 and 11.

Referring back to FIGS. 9, 10 and 11 , in another embodiment a form ofmagnet placement code can be programmed into the AIMD software (forexample, Morse code). In this case, a particular AIMD such as a cardiacpacemaker may have multiple magnet-modes. To enter each particular mode,the placements and flips are varied. For example, for AIMD magnet-modeone- or two-timed placements of FIG. 9 also require a flip asillustrated in FIG. 10 . To have the AIMD enter an alternatemagnet-mode, there might be one placement in accordance with FIG. 9 ,and then two or more flips in accordance with FIG. 10 . The number ofcombinations and permutations are large. This Morse code embodiment isnot possible with reed switches or GMR, or other non-polarity sensingAIMDs.

In summary, the present invention changes the magnet-mode of an activeimplantable medical device (AIMD) such that repeated application of aclinical magnet in a predetermined and deliberate time sequence willinduce the AIMD to enter into its designed magnet-mode. In that manner,the present invention is directed towards prevention of inadvertententry of an AIMD into magnet-mode caused by the static magnetic fieldassociated with the magnet in a portable electronic device, children'stoy, and the like. It is very important that life-saving implantablemedical devices do not enter magnet-mode unless it is done deliberately.Magnet-mode is intended as a design feature in an AIMD for a shortperiod of time when a physician interrogates the device, performs asurgical procedure, and the like. Magnet-mode was never intended forprolonged use, such as could inadvertently happen when the magnet in aportable handheld device is placed in relatively close proximity to theimplanted device. In one embodiment of the invention, the clinicalmagnet is applied close to and over the AIMD and removed a specifiednumber of times within a specified timing sequence. In anotherembodiment of the invention, the clinical magnet is applied close to andover the AIMD and flipped a specified number of times within a specifiedtiming sequence. This makes it highly unlikely that the magnet in aportable electronic device, children's toy, and the like caninadvertently and dangerously induce AIMD magnet-mode.

Although several particular embodiments of the present invention havebeen described in detail for purposes of illustration, variousmodifications may be made without departing from the scope of theinvention. Accordingly, the present invention is not to be limited,except by the appended claims.

What is claimed is:
 1. An active implantable medical device (AIMD) thatis configured to deliver electrical stimulation therapy to body tissueand/or sense electrical biological signals from body tissue, the AIMDcomprising: a) a housing containing a magnetic field-detection sensorconnected to electronic circuits, wherein the electronic circuits havebeen programmed to register when the magnetic field-detection sensordetects that a static magnet of at least a defined Gauss is in closeproximity to the AIMD as a first close proximity occurrence, and b)wherein, within a first-time window upon commencement of the first closeproximity occurrence, the electronic circuits have been programmed toregister when the magnetic field-detection sensor no longer detects thatthe static magnet is in close proximity to the AIMD as a first removaloccurrence, and c) wherein, within a second-time window uponcommencement of the first removal occurrence, the electronic circuitshave been programmed to register when the magnetic field-detectionsensor again detects that the static magnet is in close proximity to theAIMD as a second close proximity occurrence, and d) wherein uponcommencement of the second close proximity occurrence, the electroniccircuits of the AIMD have been programmed to enter into magnet-mode withelectrical stimulation therapy of the body tissue and/or electricalsensing of biological signals from the body tissue being suspended,maintained in a preset mode, and/or placed in a programmed mode.
 2. TheAIMD of claim 1, wherein, upon commencement of the second closeproximity occurrence, the electronic circuits have been programmed toremain in magnet-mode for as long as the magnetic field-detection sensordetects that the static magnet is in close proximity to the AIMD.
 3. TheAIMD of claim 1, wherein the magnetic field-detection sensor isconfigured to detect the close proximity of the static magnet having astrength of at least about 9 Gauss.
 4. The AIMD of claim 1, wherein themagnetic field-detection sensor is selected from the group of a reedswitch, a Hall-effect sensor, and a giant magnetoresistive (GMR) sensor.5. The AIMD of claim 1, wherein the first-time window upon commencementof the first close proximity occurrence has a duration of from n₁seconds to n₂ seconds, and wherein the second-time window uponcommencement of the first removal occurrence has a duration of from n₃to n₄ seconds.
 6. The AIMD of claim 5, wherein the durations of n₁seconds and n₃ seconds are the same or different, and wherein thedurations of n₂ seconds and n₄ seconds are the same or different.
 7. TheAIMD of claim 1, wherein the first-time window upon commencement of thefirst close proximity occurrence has a duration of from 2 to 10 seconds,and wherein the second-time window upon commencement of the firstremoval occurrence has a duration of from 2 to 10 seconds.
 8. The AIMDof claim 1, further comprising: a) an implanted lead wire connected tothe AIMD, wherein the lead wire extends to a distal electrode in contactwith biological cells for providing electrical stimulation therapy tothe biological cells and/or sensing electrical biological signals frombody tissue, and b) wherein, upon commencement of the second closeproximity occurrence, the electronic circuits have been programmed toenter into magnet-mode with electrical stimulation therapy of the bodytissue and/or electrical sensing of biological signals from the bodytissue being suspended, maintained in a preset mode, and/or placed in aprogrammed mode.
 9. The AIMD of claim 8, wherein, upon commencement ofthe second close proximity occurrence, the electronic circuits have beenprogrammed to remain in magnet-mode for as long as the magneticfield-detection sensor detects that the static magnet is in closeproximity to the AIMD.
 10. The AIMD of claim 1, a) wherein theelectronic circuits have been programmed to register when the magneticfield-detection sensor detects that the static magnet has either a northor a south polarity facing the AIMD as the first close proximityoccurrence, and b) wherein, within the first-time window uponcommencement of the first close proximity occurrence, the electroniccircuits have been programmed to register when the magneticfield-detection sensor no longer detects that the static magnet is inclose proximity to the AIMD as the first removal occurrence, and c)wherein, within the second-time window, the electronic circuits havebeen programmed to register when the magnetic field-detection sensordetects that the static magnet has been flipped so that the other of thenorth or the south polarity is in close proximity to the AIMD as thesecond close proximity occurrence to thereby cause the electroniccircuits of the AIMD to enter into magnet-mode with electricalstimulation therapy of the body tissue and/or electrical sensing ofbiological signals from the body tissue being suspended, maintained in apreset mode, and/or placed in a programmed mode.
 11. The AIMD of claim1, wherein the electronic circuits have been programmed to register whenthe magnetic field-detection sensor detects that the static magnet iscloser than about 15 cm or six inches as the static magnet being inclose proximity to the AIMD.
 12. An active implantable medical device(AIMD) that is configured to deliver electrical stimulation therapy tobody tissue and/or sense electrical biological signals from body tissue,the AIMD comprising: a) a housing containing a magnetic field-detectionsensor connected to electronic circuits, b) wherein the electroniccircuits have been programmed to register when the magneticfield-detection sensor detects that a static magnetic field of at leasta defined Gauss field strength is in close proximity to the AIMD as afirst close proximity occurrence, and c) wherein, within a first-timewindow upon commencement of the first close proximity occurrence, theelectronic circuits have been programmed to register when the magneticfield-detection sensor no longer detects that the static magnetic fieldis in close proximity to the AIMD as a first removal occurrence, and d)wherein, within a second-time window upon commencement of the firstremoval occurrence, the electronic circuits have been programmed toregister when the magnetic field-detection sensor again detects that thestatic magnetic field is in close proximity to the AIMD as a secondclose proximity occurrence, and e) wherein, within a time window of adefined duration upon commencement of the second close proximityoccurrence, the electronic circuits have been programmed to registerwhen the magnetic field-detection sensor detects that the staticmagnetic field is no longer in close proximity to the AIMD as a firstplus x removal occurrence, and f) wherein, within a time window of adefined duration upon commencement of the first plus x removaloccurrence, the electronic circuits have been programmed to registerwhen the magnetic field-detection sensor again detects that the staticmagnetic field is in close proximity to the AIMD as a second plus yclose proximity occurrence, and g) wherein x for the first plus xremoval occurrence ranges from 1 to 99 removal occurrences and y for thesecond plus y close proximity occurrence ranges from 1 to 100 closeproximity occurrences with y being equal to x plus 1, and h) wherein,upon commencement of the second plus y close proximity occurrence with ycounting from 1 to a maximum defined number that is not greater than 100programmed into the electronic circuits, the electronic circuits of theAIMD have been programmed to enter into magnet-mode with electricalstimulation therapy of the body tissue and/or electrical sensing ofbiological signals from the body tissue being suspended, maintained in apreset mode, and/or placed in a programmed mode.
 13. The AIMD of claim12, wherein the time windows upon commencement of the first closeproximity occurrence, upon commencement of the second close proximityoccurrence, and upon commencement of the second plus y close proximityoccurrence are the same or different.
 14. The AIMD of claim 12, whereinthe time window of the defined duration upon commencement of the firstplus x removal occurrence is the same or different as the second-timewindow upon commencement of the first removal occurrence.
 15. The AIMDof claim 12, wherein, upon commencement of the second plus y closeproximity occurrence with y being of the maximum defined number that isnot greater than 100 programmed into the electronic circuits to causethe electronic circuits to enter into magnet-mode, the electroniccircuits have been programmed to remain in magnet-mode for as long asthe magnetic field-detection sensor detects that the static magneticfield is in close proximity to the AIMD.
 16. The AIMD of claim 12,wherein the first-time window upon commencement of the first closeproximity occurrence is of at least n₁ seconds to a maximum of n₂seconds, and wherein the second-time window upon commencement of thefirst removal occurrence is of at least n₃ seconds to a maximum of n₄seconds.
 17. The AIMD of claim 16, wherein the durations of n₁ secondsand n₃ seconds are the same or different, and wherein the durations ofn₂ seconds and n₄ seconds are the same or different.
 18. The AIMD ofclaim 12, a) wherein the electronic circuits have been programmed toregister when the magnetic field-detection sensor detects that thestatic magnet has either a north or a south polarity facing the AIMD asthe first close proximity occurrence, and b) wherein, within thefirst-time window upon commencement of the first close proximityoccurrence, the electronic circuits have been programmed to registerwhen the magnetic field-detection sensor no longer detects that thestatic magnet is in close proximity to the AIMD as the first removaloccurrence, and c) wherein, within the second-time window, theelectronic circuits have been programmed to register when the magneticfield-detection sensor detects that the static magnet has been flippedso that the other of the north or the south polarity is in closeproximity to the AIMD as the second close proximity occurrence, and d)wherein, within the time window of the defined duration uponcommencement of the second close proximity occurrence, the electroniccircuits have been programmed to register when the magneticfield-detection sensor no longer detects that the static magnetic fieldis in close proximity to the AIMD as the first plus x removaloccurrence, and f) wherein, when y for the second plus y close proximityoccurrence is an odd number, the electronic circuits have beenprogrammed to register when the one of the north or the south polarityof the static magnet that registered as the first close proximityoccurrence is in close proximity to the AIMD as the second plus y closeproximity occurrence, and g) wherein, when y for the second plus y closeproximity occurrence is an even number, the electronic circuits havebeen programmed to register when the one of the north or the southpolarity of the static magnet that registered as the second closeproximity occurrence is in close proximity to the AIMD as the secondplus y close proximity occurrence, and h) wherein, when the maximumdefined number for y is reached, the electronic circuits of the AIMDhave been programmed to enter into magnet-mode with electricalstimulation therapy of the body tissue and/or electrical sensing ofbiological signals from the body tissue being suspended, maintained in apreset mode, and/or placed in a programmed mode.
 19. The AIMD of claim12, wherein the magnetic field has a strength of at least 9 Gauss fieldstrength and is in close proximity to the AIMD when the static magneticfield is closer than about 15 cm or six inches from the AIMD.
 20. Amethod for an active implantable medical device (AIMD) to enter intomagnet-mode, the method comprising the steps of: a) providing an AIMDthat is implanted in body tissue and configured to deliver electricalstimulation therapy to body tissue and/or sense electrical biologicalsignals from body tissue, wherein the AIMD has a housing containing amagnetic field-detection sensor connected to electronic circuits, andwherein the electronic circuits have been programmed to register whenthe magnetic field-detection sensor detects that a static magnet of atleast a defined Gauss field strength is in close proximity to the AIMDas a close proximity occurrence and when the static magnet is not inclose proximity to the AIMD as a removal occurrence; b) providing astatic magnet of a defined Gauss field strength; c) moving the staticmagnet into close proximity to the AIMD so that the electronic circuitsregister when the magnetic field-detection sensor detects that thestatic magnet is in close proximity to the AIMD as a first closeproximity occurrence; d) then, within a first-time window uponcommencement of the first close proximity occurrence, moving the staticmagnet away from the AIMD so that the electronic circuits register whenthe magnetic field-detection sensor no longer detects the static magnetas a first removal occurrence; and e) then, within a second-time windowupon commencement of the first removal occurrence, moving the staticmagnet back into close proximity to the AIMD with the electroniccircuits registering when the magnetic field-detection sensor detectsthat the static magnet is in close proximity to the AIMD as a secondclose proximity occurrence, f) so that upon commencement of the secondclose proximity occurrence, the electronic circuits of the AIMD enterinto magnet-mode with electrical stimulation therapy of the body tissueand/or electrical sensing of biological signals from the body tissuebeing suspended, maintained in a preset mode, and/or placed in aprogrammed mode.
 21. The method of claim 20, including programming theelectronic circuits to remain in magnet-mode upon commencement of thesecond close proximity occurrence for as long as the magneticfield-detection sensor detects that the static magnet is in closeproximity to the AIMD.
 22. The method of claim 20, including providingthe static magnet having a strength of at least about 9 Gauss fieldstrength.
 23. The method of claim 20, including selecting the magneticfield-detection sensor from the group of a reed switch, a Hall-effectsensor, and a giant magnetoresistive (GMR) sensor.
 24. The method ofclaim 20, including programming the electronic circuits so that thefirst-time window upon commencement of the first close proximityoccurrence has a duration of from 2 to 10 seconds, and so that thesecond-time window upon commencement of the first removal occurrence hasa time duration of from 2 to 10 seconds.
 25. The method of claim 20,further including: a) connecting the AIMD to a lead wire extending to adistal electrode in contact with biological cells for providing theelectrical stimulation therapy to the biological cells and/or sensingelectrical biological signals from body tissue; and b) then, within thesecond-time window upon commencement of the first removal occurrence,moving the static magnet back into close proximity to the AIMD so thatthe magnetic field-detection sensor again detects that the static magnetis in close proximity to the AIMD as a second close proximityoccurrence, thereby causing the electronic circuits to enter intomagnet-mode so that the AIMD discontinues providing electricalstimulation therapy to and/or sensing biological signals from the bodytissue, maintains a preset mode for providing electrical stimulationtherapy to and/or sensing biological signals from the body tissue,and/or is placed in a programmed mode for providing electricalstimulation therapy to and/or sensing biological signals from bodytissue.
 26. The method of claim 25, including programming the electroniccircuits to remain in magnet-mode upon commencement of the second closeproximity occurrence for as long as the magnetic field-detection sensordetects that the static magnet is in close proximity to the AIMD. 27.The method of claim 20, including programming the electronic circuitsto: a) register when the magnetic field-detection sensor detects thatthe static magnet has either a north or a south polarity facing the AIMDas the first close proximity occurrence, and b) then, within thefirst-time window upon commencement of the first close proximityoccurrence, removing the static magnet from being in close proximity tothe AIMD so that the magnetic field-detection sensor no longer detectsthat the static magnet is in close proximity to the AIMD as the firstremoval occurrence, and c) then, within the second-time window uponcommencement of the first removal occurrence, flipping and moving thestatic magnet into close proximity to the AIMD so that the magneticfield-detection sensor detects the other of the north and the southpolarity of the static magnet as the second close proximity occurrence,thereby causing the electronic circuits of the AIMD to enter intomagnet-mode with electrical stimulation therapy of the body tissueand/or electrical sensing of biological signals from the body tissuebeing suspended, maintained in a preset mode, and/or placed in aprogrammed mode.
 28. The method of claim 27, including programming theelectronic circuits to remain in magnet-mode upon commencement of thesecond close proximity occurrence for as long as the magneticfield-detection sensor detects that the static magnet is in closeproximity to the AIMD.
 29. The method of claim 20, including programmingthe electronic circuits to register when the magnetic field-detectionsensor detects that the static magnet is closer than about 15 cm or sixinches as the static magnet being in close proximity to the AIMD.